diff --git a/CMakeLists.txt b/CMakeLists.txt
index a847838be..a2ab8bde2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -26,6 +26,15 @@ include(ECMSetupVersion)
 include(ECMAddAppIcon)
 include(ECMQtDeclareLoggingCategory)
 include(ECMPoQmTools)
+if (QT_MAJOR_VERSION STREQUAL "6")
+    set(QT_MIN_VERSION "6.4.0")
+    set(KF_MIN_VERSION "5.240.0")
+    set(KF_MAJOR_VERSION "6")
+else()
+    set(QT_MIN_VERSION "5.15.0")
+    set(KF_MIN_VERSION "5.78.0")
+    set(KF_MAJOR_VERSION "5")
+endif()
 
 # Output dirs (like ECM 5.38 does)
 set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_BINARY_DIR}/lib")
@@ -49,26 +58,30 @@ endif()
 # Defines that are always set
 add_definitions(-DQT_NO_URL_CAST_FROM_STRING -DQT_USE_QSTRINGBUILDER -DQT_NO_CAST_TO_ASCII)
 
-# Mandatory: Qt5
-set(QT_MIN_VERSION "5.15.0")
-find_package(Qt5 ${QT_MIN_VERSION} REQUIRED COMPONENTS Core Widgets Network Sql QuickWidgets PrintSupport WebChannel)
-find_package(Qt5WebEngine ${QT_MIN_VERSION} REQUIRED)
-find_package(Qt5WebEngineWidgets ${QT_MIN_VERSION} REQUIRED)
+# Mandatory: Qt5/6
+find_package(Qt${QT_MAJOR_VERSION} ${QT_MIN_VERSION} REQUIRED COMPONENTS Core Widgets Network Sql QuickWidgets PrintSupport WebChannel)
+if (QT_MAJOR_VERSION STREQUAL "6")
+    find_package(Qt6WebEngineCore ${QT_MIN_VERSION} REQUIRED)
+    find_package(Qt6WebEngineWidgets ${QT_MIN_VERSION} REQUIRED)
+else()
+    find_package(Qt5WebEngine ${QT_MIN_VERSION} REQUIRED)
+    find_package(Qt5WebEngineWidgets ${QT_MIN_VERSION} REQUIRED)
+endif()
 if (BUILD_TESTING)
-    find_package(Qt5 ${QT_MIN_VERSION} REQUIRED COMPONENTS Test)
+    find_package(Qt${QT_MAJOR_VERSION} ${QT_MIN_VERSION} REQUIRED COMPONENTS Test)
 endif()
 if (NOT DISABLE_DBUS)
-    find_package(Qt5 ${QT_MIN_VERSION} REQUIRED COMPONENTS DBus)
+    find_package(Qt${QT_MAJOR_VERSION} ${QT_MIN_VERSION} REQUIRED COMPONENTS DBus)
 endif()
 
 if (UNIX AND NOT APPLE AND NOT NO_X11)
     add_definitions(-DQZ_WS_X11)
     find_package(XCB REQUIRED COMPONENTS XCB UTIL)
-    find_package(Qt5 ${QT_MIN_VERSION} REQUIRED COMPONENTS X11Extras)
+    find_package(Qt${QT_MAJOR_VERSION} ${QT_MIN_VERSION} REQUIRED COMPONENTS X11Extras)
 endif()
 if (WIN32)
     add_definitions(-DW7API)
-    find_package(Qt5 ${QT_MIN_VERSION} REQUIRED COMPONENTS WinExtras)
+    find_package(Qt${QT_MAJOR_VERSION} ${QT_MIN_VERSION} REQUIRED COMPONENTS WinExtras)
 
     # taken from https://stackoverflow.com/a/40217291
     macro(get_WIN32_WINNT version)
@@ -93,15 +106,19 @@ if (WIN32)
     add_definitions(-D_WIN32_WINNT=${ver})
 endif()
 
+if (QT_MAJOR_VERSION STREQUAL "6")
+    find_package(Qt6Core5Compat)
+endif()
+
 # Mandatory: OpenSSL
 find_package(OpenSSL REQUIRED)
 
-# Mandatory: KF5
-find_package(KF5 REQUIRED COMPONENTS Archive)
+# Mandatory: KF5/6
+find_package(KF${KF_MAJOR_VERSION} REQUIRED COMPONENTS Archive)
 
 # KF5I18n: Mandatory with downloaded translations (only for ki18n_install)
 if (EXISTS "${CMAKE_SOURCE_DIR}/po")
-    find_package(KF5I18n REQUIRED)
+    find_package(KF${KF_MAJOR_VERSION}I18n REQUIRED)
 endif()
 
 # Optional: GnomeKeyring
@@ -114,34 +131,47 @@ if (PKG_CONFIG_FOUND)
 endif()
 
 # Optional: KWallet, KIO, KCrash, KCoreAddons
-set(KF5_MIN_VERSION "5.78.0")
-find_package(KF5Wallet ${KF5_MIN_VERSION} CONFIG)
-set_package_properties(KF5Wallet PROPERTIES DESCRIPTION "KDE Frameworks Integration plugin" TYPE OPTIONAL)
-find_package(KF5KIO ${KF5_MIN_VERSION} CONFIG)
-set_package_properties(KF5KIO PROPERTIES DESCRIPTION "KDE Frameworks Integration plugin" TYPE OPTIONAL)
-find_package(KF5Crash ${KF5_MIN_VERSION} CONFIG)
-set_package_properties(KF5Crash PROPERTIES DESCRIPTION "KDE Frameworks Integration plugin" TYPE OPTIONAL)
-find_package(KF5CoreAddons ${KF5_MIN_VERSION} CONFIG)
-set_package_properties(KF5CoreAddons PROPERTIES DESCRIPTION "KDE Frameworks Integration plugin" TYPE OPTIONAL)
-find_package(KF5Purpose ${KF5_MIN_VERSION} CONFIG)
-find_package(KF5JobWidgets ${KF5_MIN_VERSION} CONFIG)
-set_package_properties(KF5JobWidgets PROPERTIES DESCRIPTION "KDE Frameworks Integration plugin" TYPE OPTIONAL)
-set_package_properties(KF5Purpose PROPERTIES DESCRIPTION "KDE Frameworks Integration plugin" TYPE OPTIONAL)
-if (KF5Wallet_FOUND AND KF5KIO_FOUND AND KF5Crash_FOUND AND KF5CoreAddons_FOUND AND KF5Purpose_FOUND AND KF5JobWidgets_FOUND)
+find_package(KF${KF_MAJOR_VERSION}Wallet ${KF_MIN_VERSION} CONFIG)
+set_package_properties(KF${KF_MAJOR_VERSION}Wallet PROPERTIES DESCRIPTION "KDE Frameworks Integration plugin" TYPE OPTIONAL)
+find_package(KF${KF_MAJOR_VERSION}KIO ${KF_MIN_VERSION} CONFIG)
+set_package_properties(KF${KF_MAJOR_VERSION}KIO PROPERTIES DESCRIPTION "KDE Frameworks Integration plugin" TYPE OPTIONAL)
+find_package(KF${KF_MAJOR_VERSION}Crash ${KF_MIN_VERSION} CONFIG)
+set_package_properties(KF${KF_MAJOR_VERSION}Crash PROPERTIES DESCRIPTION "KDE Frameworks Integration plugin" TYPE OPTIONAL)
+find_package(KF${KF_MAJOR_VERSION}CoreAddons ${KF_MIN_VERSION} CONFIG)
+set_package_properties(KF${KF_MAJOR_VERSION}CoreAddons PROPERTIES DESCRIPTION "KDE Frameworks Integration plugin" TYPE OPTIONAL)
+find_package(KF${KF_MAJOR_VERSION}Purpose ${KF_MIN_VERSION} CONFIG)
+set_package_properties(KF${KF_MAJOR_VERSION}Purpose PROPERTIES DESCRIPTION "KDE Frameworks Integration plugin" TYPE OPTIONAL)
+find_package(KF${KF_MAJOR_VERSION}JobWidgets ${KF_MIN_VERSION} CONFIG)
+set_package_properties(KF${KF_MAJOR_VERSION}JobWidgets PROPERTIES DESCRIPTION "KDE Frameworks Integration plugin" TYPE OPTIONAL)
+if (KF${KF_MAJOR_VERSION}Wallet_FOUND AND KF${KF_MAJOR_VERSION}KIO_FOUND AND KF${KF_MAJOR_VERSION}Crash_FOUND AND KF${KF_MAJOR_VERSION}CoreAddons_FOUND AND KF${KF_MAJOR_VERSION}Purpose_FOUND AND KF${KF_MAJOR_VERSION}JobWidgets_FOUND)
     set(ENABLE_KDE_FRAMEWORKS_INTEGRATION_PLUGIN TRUE)
 endif()
 
 # Optional: PySide2
 option(BUILD_PYTHON_SUPPORT "Support for Python plugins" ON)
 if (BUILD_PYTHON_SUPPORT)
-    find_package(PySide2 "2.0.0")
-    find_package(Shiboken2 "2.0.0")
-    find_package(Python3 COMPONENTS Development)
-    set_package_properties(PySide2 PROPERTIES DESCRIPTION "Python plugins" TYPE OPTIONAL)
-    set_package_properties(Shiboken2 PROPERTIES DESCRIPTION "Python plugins" TYPE OPTIONAL)
-    set_package_properties(Python3 PROPERTIES DESCRIPTION "Python plugins" TYPE OPTIONAL)
-    if (PySide2_FOUND AND Shiboken2_FOUND AND Python3_FOUND)
-        set(ENABLE_PYTHON_PLUGINS TRUE)
+    if (QT_MAJOR_VERSION STREQUAL "6")
+        # Optional: PySide6
+        find_package(PySide6 "6.4.0")
+        find_package(Shiboken6 "6.4.0")
+        find_package(Python3 COMPONENTS Development)
+        set_package_properties(PySide6 PROPERTIES DESCRIPTION "Python plugins" TYPE OPTIONAL)
+        set_package_properties(Shiboken6 PROPERTIES DESCRIPTION "Python plugins" TYPE OPTIONAL)
+        set_package_properties(Python3 PROPERTIES DESCRIPTION "Python plugins" TYPE OPTIONAL)
+        if (PySide6_FOUND AND Shiboken6_FOUND AND Python3_FOUND)
+            set(ENABLE_PYTHON_PLUGINS TRUE)
+        endif()
+    else()
+        # Optional: PySide2
+        find_package(PySide2 "2.0.0")
+        find_package(Shiboken2 "2.0.0")
+        find_package(Python3 COMPONENTS Development)
+        set_package_properties(PySide2 PROPERTIES DESCRIPTION "Python plugins" TYPE OPTIONAL)
+        set_package_properties(Shiboken2 PROPERTIES DESCRIPTION "Python plugins" TYPE OPTIONAL)
+        set_package_properties(Python3 PROPERTIES DESCRIPTION "Python plugins" TYPE OPTIONAL)
+        if (PySide2_FOUND AND Shiboken2_FOUND AND Python3_FOUND)
+            set(ENABLE_PYTHON_PLUGINS TRUE)
+        endif()
     endif()
 endif()
 
diff --git a/autotests/qml/qmluserscriptapitest.cpp b/autotests/qml/qmluserscriptapitest.cpp
index 3a7e28cb8..c7e90a045 100644
--- a/autotests/qml/qmluserscriptapitest.cpp
+++ b/autotests/qml/qmluserscriptapitest.cpp
@@ -41,7 +41,7 @@ void QmlUserScriptApiTest::testCount()
 void QmlUserScriptApiTest::testSize()
 {
     int size = m_testHelper.evaluate("Falkon.UserScripts.size").toInt();
-    QCOMPARE(size, mApp->webProfile()->scripts()->size());
+    QCOMPARE(size, mApp->webProfile()->scripts()->count());
 }
 
 void QmlUserScriptApiTest::testEmpty()
diff --git a/src/lib/3rdparty/fancytabwidget.cpp b/src/lib/3rdparty/fancytabwidget.cpp
index 582f833b5..384a64fdf 100644
--- a/src/lib/3rdparty/fancytabwidget.cpp
+++ b/src/lib/3rdparty/fancytabwidget.cpp
@@ -39,10 +39,11 @@
 #include <QSignalMapper>
 #include <QSplitter>
 #include <QStackedLayout>
-#include <QStyleOptionTabV3>
+#include <QStyleOptionTab>
 #include <QToolButton>
 #include <QToolTip>
 #include <QVBoxLayout>
+#include <QActionGroup>
 //#include <QWindowsStyle>
 
 using namespace Core;
@@ -306,7 +307,11 @@ void FancyTabBar::paintEvent(QPaintEvent* event)
     }
 }
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 void FancyTab::enterEvent(QEvent*)
+#else
+void FancyTab::enterEvent(QEnterEvent*)
+#endif
 {
     fadeIn();
 }
diff --git a/src/lib/3rdparty/fancytabwidget.h b/src/lib/3rdparty/fancytabwidget.h
index d7b87851d..eceff02c8 100644
--- a/src/lib/3rdparty/fancytabwidget.h
+++ b/src/lib/3rdparty/fancytabwidget.h
@@ -86,7 +86,11 @@ public:
     QString text;
 
 protected:
-    void enterEvent(QEvent*) override;
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
+    void enterEvent(QEvent *event) override;
+#else
+    void enterEvent(QEnterEvent *event) override;
+#endif
     void leaveEvent(QEvent*) override;
 
 private:
diff --git a/src/lib/3rdparty/qtsingleapplication/qtlocalpeer.cpp b/src/lib/3rdparty/qtsingleapplication/qtlocalpeer.cpp
index 83e397c94..3160d6743 100644
--- a/src/lib/3rdparty/qtsingleapplication/qtlocalpeer.cpp
+++ b/src/lib/3rdparty/qtsingleapplication/qtlocalpeer.cpp
@@ -44,6 +44,10 @@
 #include <QDataStream>
 #include <QTime>
 
+#if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
+#include <QRegExp>
+#endif
+
 #include "../config.h"
 #if defined(Q_OS_LINUX) && !defined(DISABLE_DBUS)
 #define USE_DBUS
@@ -110,7 +114,11 @@ QtLocalPeer::QtLocalPeer(QObject* parent, const QString &appId)
 #endif
         prefix = id.section(QLatin1Char('/'), -1);
     }
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     prefix.remove(QRegExp("[^a-zA-Z]"));
+#else
+    prefix = QRegExp("[^a-zA-Z]").removeIn(prefix);
+#endif
     prefix.truncate(6);
 
     QByteArray idc = id.toUtf8();
diff --git a/src/lib/3rdparty/stylehelper.cpp b/src/lib/3rdparty/stylehelper.cpp
index ca0372aa7..9324af89e 100644
--- a/src/lib/3rdparty/stylehelper.cpp
+++ b/src/lib/3rdparty/stylehelper.cpp
@@ -160,7 +160,11 @@ void StyleHelper::verticalGradient(QPainter* painter, const QRect &spanRect, con
                      clipRect.height(), keyColor.rgb());
 
         QPixmap pixmap;
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
         if (!QPixmapCache::find(key, pixmap)) {
+#else
+        if (!QPixmapCache::find(key, &pixmap)) {
+#endif
             pixmap = QPixmap(clipRect.size());
             QPainter p(&pixmap);
             QRect rect(0, 0, clipRect.width(), clipRect.height());
@@ -183,7 +187,11 @@ void StyleHelper::drawIconWithShadow(const QIcon &icon, const QRect &rect,
     QPixmap cache;
     QString pixmapName = QSL("icon %0 %1 %2").arg(icon.cacheKey()).arg(iconMode).arg(rect.height());
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     if (!QPixmapCache::find(pixmapName, cache)) {
+#else
+    if (!QPixmapCache::find(pixmapName, &cache)) {
+#endif
         QPixmap px = icon.pixmap(rect.size(), iconMode);
         px.setDevicePixelRatio(qApp->devicePixelRatio());
         cache = QPixmap(px.size() + QSize(radius * 2, radius * 2));
diff --git a/src/lib/CMakeLists.txt b/src/lib/CMakeLists.txt
index 806800aeb..d66a8582c 100644
--- a/src/lib/CMakeLists.txt
+++ b/src/lib/CMakeLists.txt
@@ -577,20 +577,41 @@ qt_add_resources(SRCS
 
 add_library(FalkonPrivate SHARED ${SRCS} ${LOGGING_SRCS})
 
-get_property(QT_WEBENGINE_INCLUDE_DIRS TARGET Qt::WebEngine PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
+if (QT_MAJOR_VERSION STREQUAL "6")
+    get_property(QT_WEBENGINE_INCLUDE_DIRS TARGET Qt6::WebEngineCore PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
+else()
+    get_property(QT_WEBENGINE_INCLUDE_DIRS TARGET Qt::WebEngine PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
+endif()
+
 target_include_directories(FalkonPrivate SYSTEM PUBLIC ${QT_WEBENGINE_INCLUDE_DIRS})
 
-target_link_libraries(FalkonPrivate
-    Qt::Widgets
-    Qt::WebEngineWidgets
-    Qt::Network
-    Qt::Sql
-    Qt::PrintSupport
-    Qt::QuickWidgets
-    Qt::WebChannel
-    KF5::Archive
-    ${OPENSSL_CRYPTO_LIBRARY}
-)
+if (QT_MAJOR_VERSION STREQUAL "6")
+    target_link_libraries(FalkonPrivate
+        Qt6::Widgets
+        Qt6::WebEngineWidgets
+        Qt6::Network
+        Qt6::NetworkPrivate
+        Qt6::Sql
+        Qt6::PrintSupport
+        Qt6::QuickWidgets
+        Qt6::WebChannel
+        Qt6::Core5Compat
+        KF6::Archive
+        ${OPENSSL_CRYPTO_LIBRARY}
+    )
+else()
+    target_link_libraries(FalkonPrivate
+        Qt::Widgets
+        Qt::WebEngineWidgets
+        Qt::Network
+        Qt::Sql
+        Qt::PrintSupport
+        Qt::QuickWidgets
+        Qt::WebChannel
+        KF5::Archive
+        ${OPENSSL_CRYPTO_LIBRARY}
+    )
+endif()
 
 if (HAVE_LIBINTL)
     target_include_directories(FalkonPrivate SYSTEM PUBLIC ${Intl_INCLUDE_DIRS})
diff --git a/src/lib/adblock/adblockmanager.cpp b/src/lib/adblock/adblockmanager.cpp
index 98d111235..6d36445a7 100644
--- a/src/lib/adblock/adblockmanager.cpp
+++ b/src/lib/adblock/adblockmanager.cpp
@@ -296,7 +296,11 @@ void AdBlockManager::load()
         }
 
         QTextStream textStream(&file);
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
         textStream.setCodec("UTF-8");
+#else
+        textStream.setEncoding(QStringConverter::Utf8);
+#endif
         QString title = textStream.readLine(1024).remove(QLatin1String("Title: "));
         QUrl url = QUrl(textStream.readLine(1024).remove(QLatin1String("Url: ")));
 
diff --git a/src/lib/adblock/adblockrule.cpp b/src/lib/adblock/adblockrule.cpp
index 10ceac2f6..2eaddb864 100644
--- a/src/lib/adblock/adblockrule.cpp
+++ b/src/lib/adblock/adblockrule.cpp
@@ -53,9 +53,40 @@
 #include <QWebEnginePage>
 #include <QWebEngineUrlRequestInfo>
 
+#if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
+#include <QtCore/private/qurl_p.h>
+#include <QtNetwork/private/qtldurl_p.h>
+#endif
+
+static QString getTopLevelDomain(const QUrl &url)
+{
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
+    return url.topLevelDomain();
+#else
+    // QUrl::topLevelDomain() was removed in Qt6.
+    // The following is copied from the old "qTopLevelDomain" code in Qt6::Network.
+    // It was removed in this commit: https://github.com/qt/qtbase/commit/50b30976837be0969efdccced68cfb584d99981a
+    const QString domainLower = url.host().toLower();
+    QVector<QStringView> sections = QStringView{domainLower}.split(QLatin1Char('.'), Qt::SkipEmptyParts);
+    if (sections.isEmpty())
+        return QString();
+
+    QString level, tld;
+    for (int j = sections.count() - 1; j >= 0; --j) {
+        level.prepend(QLatin1Char('.') + sections.at(j));
+        if (qIsEffectiveTLD(QStringView{level}.right(level.size() - 1)))
+            tld = level;
+    }
+
+    //return qt_ACE_do(tld, ToAceOnly, AllowLeadingDot, {});
+    // TODO - QUrl::toAce() uses ForbidLeadingDot, while the old QUrl::topLevelDomain() used AllowLeadingDot. Does this matter?
+    return QString(QUrl::toAce(tld));
+#endif
+}
+
 static QString toSecondLevelDomain(const QUrl &url)
 {
-    const QString topLevelDomain = url.topLevelDomain();
+    const QString topLevelDomain = getTopLevelDomain(url);
     const QString urlHost = url.host();
 
     if (topLevelDomain.isEmpty() || urlHost.isEmpty()) {
diff --git a/src/lib/adblock/adblocksubscription.cpp b/src/lib/adblock/adblocksubscription.cpp
index c8cf58686..4ef128ea2 100644
--- a/src/lib/adblock/adblocksubscription.cpp
+++ b/src/lib/adblock/adblocksubscription.cpp
@@ -103,7 +103,11 @@ void AdBlockSubscription::loadSubscription(const QStringList &disabledRules)
     }
 
     QTextStream textStream(&file);
-    textStream.setCodec("UTF-8");
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
+        textStream.setCodec("UTF-8");
+#else
+        textStream.setEncoding(QStringConverter::Utf8);
+#endif
     // Header is on 3rd line
     textStream.readLine(1024);
     textStream.readLine(1024);
@@ -306,7 +310,11 @@ void AdBlockCustomList::loadSubscription(const QStringList &disabledRules)
 
     if (file.open(QFile::WriteOnly | QFile::Append)) {
         QTextStream stream(&file);
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
         stream.setCodec("UTF-8");
+#else
+        stream.setEncoding(QStringConverter::Utf8);
+#endif
 
         if (!rules.contains(ddg1 + QL1S("\n")))
             stream << ddg1 << Qt::endl;
@@ -329,7 +337,11 @@ void AdBlockCustomList::saveSubscription()
     }
 
     QTextStream textStream(&file);
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     textStream.setCodec("UTF-8");
+#else
+    textStream.setEncoding(QStringConverter::Utf8);
+#endif
     textStream << "Title: " << title() << Qt::endl;
     textStream << "Url: " << url().toString() << Qt::endl;
     textStream << "[Adblock Plus 1.1.1]" << Qt::endl;
diff --git a/src/lib/app/browserwindow.cpp b/src/lib/app/browserwindow.cpp
index bf1381d73..e4806bb83 100644
--- a/src/lib/app/browserwindow.cpp
+++ b/src/lib/app/browserwindow.cpp
@@ -72,11 +72,14 @@
 #include <QWebEngineHistory>
 #include <QWebEngineSettings>
 #include <QMessageBox>
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 #include <QDesktopWidget>
+#endif
 #include <QToolTip>
 #include <QScrollArea>
 #include <QCollator>
 #include <QTemporaryFile>
+#include <QActionGroup>
 
 #ifdef QZ_WS_X11
 #include <QX11Info>
@@ -400,7 +403,11 @@ void BrowserWindow::setupUi()
     m_statusBar->addButton(downloadsButton);
     m_navigationToolbar->addToolButton(downloadsButton);
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     QDesktopWidget* desktop = mApp->desktop();
+#else
+    auto desktop = QGuiApplication::primaryScreen();
+#endif
     int windowWidth = desktop->availableGeometry().width() / 1.3;
     int windowHeight = desktop->availableGeometry().height() / 1.3;
 
@@ -1341,7 +1348,7 @@ void BrowserWindow::keyPressEvent(QKeyEvent* event)
         break;
 
     case Qt::Key_Backtab:
-        if (event->modifiers() == (Qt::ControlModifier + Qt::ShiftModifier)) {
+        if (event->modifiers() == (Qt::ControlModifier | Qt::ShiftModifier)) {
             static_cast<QObject*>(m_tabWidget)->event(event);
         }
         break;
diff --git a/src/lib/app/mainapplication.cpp b/src/lib/app/mainapplication.cpp
index 53e6cb062..89a876fd5 100644
--- a/src/lib/app/mainapplication.cpp
+++ b/src/lib/app/mainapplication.cpp
@@ -62,7 +62,9 @@
 #include <QDir>
 #include <QStandardPaths>
 #include <QWebEngineProfile>
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 #include <QWebEngineDownloadItem>
+#endif
 #include <QWebEngineScriptCollection>
 #include <QRegularExpression>
 #include <QtWebEngineWidgetsVersion>
@@ -930,7 +932,11 @@ void MainApplication::runDeferredPostLaunchActions()
     checkOptimizeDatabase();
 }
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 void MainApplication::downloadRequested(QWebEngineDownloadItem *download)
+#else
+void MainApplication::downloadRequested(QWebEngineDownloadRequest *download)
+#endif
 {
     downloadManager()->download(download);
 }
@@ -1187,10 +1193,16 @@ void MainApplication::setUserStyleSheet(const QString &filePath)
 
     const QString name = QStringLiteral("_falkon_userstylesheet");
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     QWebEngineScript oldScript = m_webProfile->scripts()->findScript(name);
     if (!oldScript.isNull()) {
         m_webProfile->scripts()->remove(oldScript);
     }
+#else
+    for (const QWebEngineScript &oldScript : m_webProfile->scripts()->find(name)) {
+        m_webProfile->scripts()->remove(oldScript);
+    }
+#endif
 
     if (userCss.isEmpty())
         return;
diff --git a/src/lib/app/mainapplication.h b/src/lib/app/mainapplication.h
index 5bffe26b2..aea5c8270 100644
--- a/src/lib/app/mainapplication.h
+++ b/src/lib/app/mainapplication.h
@@ -31,7 +31,11 @@ class QMenu;
 class QWebEngineProfile;
 class QWebEngineSettings;
 class QNetworkAccessManager;
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 class QWebEngineDownloadItem;
+#else
+class QWebEngineDownloadRequest;
+#endif
 
 class History;
 class AutoFill;
@@ -146,7 +150,11 @@ private Q_SLOTS:
     void onFocusChanged();
     void runDeferredPostLaunchActions();
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     void downloadRequested(QWebEngineDownloadItem *download);
+#else
+    void downloadRequested(QWebEngineDownloadRequest *download);
+#endif
 
 private:
     enum PostLaunchAction {
diff --git a/src/lib/app/qzcommon.h b/src/lib/app/qzcommon.h
index 5b51c3cdf..3d43426ca 100644
--- a/src/lib/app/qzcommon.h
+++ b/src/lib/app/qzcommon.h
@@ -20,7 +20,7 @@
 
 #include <QDebug>
 #include <QFlags>
-#include <QtWebEngine/QtWebEngineVersion>
+#include <QtWebEngineCore/QtWebEngineCoreVersion>
 
 #ifdef FALKON_SHAREDLIBRARY
 #define FALKON_EXPORT Q_DECL_EXPORT
diff --git a/src/lib/autofill/autofill.cpp b/src/lib/autofill/autofill.cpp
index 8c54356e6..d191a59ca 100644
--- a/src/lib/autofill/autofill.cpp
+++ b/src/lib/autofill/autofill.cpp
@@ -249,7 +249,11 @@ QByteArray AutoFill::exportPasswords()
     QByteArray output;
 
     QXmlStreamWriter stream(&output);
-    stream.setCodec("UTF-8");
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
+        stream.setCodec("UTF-8");
+#else
+        stream.setEncoding(QStringConverter::Utf8);
+#endif
     stream.setAutoFormatting(true);
 
     stream.writeStartDocument();
diff --git a/src/lib/bookmarks/bookmarksexport/htmlexporter.cpp b/src/lib/bookmarks/bookmarksexport/htmlexporter.cpp
index edd82caa8..e0e78e994 100644
--- a/src/lib/bookmarks/bookmarksexport/htmlexporter.cpp
+++ b/src/lib/bookmarks/bookmarksexport/htmlexporter.cpp
@@ -49,7 +49,11 @@ bool HtmlExporter::exportBookmarks(BookmarkItem* root)
     }
 
     QTextStream stream(&file);
-    stream.setCodec("UTF-8");
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
+        stream.setCodec("UTF-8");
+#else
+        stream.setEncoding(QStringConverter::Utf8);
+#endif
 
     stream << "<!DOCTYPE NETSCAPE-Bookmark-file-1>" << Qt::endl;
     stream << "<!-- This is an automatically generated file." << Qt::endl;
diff --git a/src/lib/bookmarks/bookmarksimport/operaimporter.cpp b/src/lib/bookmarks/bookmarksimport/operaimporter.cpp
index 6e300cbd8..e8dd2d4d3 100644
--- a/src/lib/bookmarks/bookmarksimport/operaimporter.cpp
+++ b/src/lib/bookmarks/bookmarksimport/operaimporter.cpp
@@ -25,7 +25,11 @@
 OperaImporter::OperaImporter(QObject* parent)
     : BookmarksImporter(parent)
 {
-    m_stream.setCodec("UTF-8");
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
+        m_stream.setCodec("UTF-8");
+#else
+        m_stream.setEncoding(QStringConverter::Utf8);
+#endif
 }
 
 QString OperaImporter::description() const
diff --git a/src/lib/bookmarks/bookmarksmanager.h b/src/lib/bookmarks/bookmarksmanager.h
index 41b48a3c0..6192fdf01 100644
--- a/src/lib/bookmarks/bookmarksmanager.h
+++ b/src/lib/bookmarks/bookmarksmanager.h
@@ -23,6 +23,8 @@
 
 #include "qzcommon.h"
 
+#include "bookmarkitem.h"
+
 namespace Ui
 {
 class BookmarksManager;
@@ -32,7 +34,6 @@ class QUrl;
 
 class BrowserWindow;
 class Bookmarks;
-class BookmarkItem;
 
 class FALKON_EXPORT BookmarksManager : public QWidget
 {
diff --git a/src/lib/bookmarks/bookmarksmodel.cpp b/src/lib/bookmarks/bookmarksmodel.cpp
index bed51625b..8d3d9f94b 100644
--- a/src/lib/bookmarks/bookmarksmodel.cpp
+++ b/src/lib/bookmarks/bookmarksmodel.cpp
@@ -22,6 +22,7 @@
 #include <QApplication>
 #include <QTimer>
 #include <QStyle>
+#include <QIODevice>
 
 //#define BOOKMARKSMODEL_DEBUG
 
diff --git a/src/lib/bookmarks/bookmarkstoolbar.cpp b/src/lib/bookmarks/bookmarkstoolbar.cpp
index 517a40b63..23f895a11 100644
--- a/src/lib/bookmarks/bookmarkstoolbar.cpp
+++ b/src/lib/bookmarks/bookmarkstoolbar.cpp
@@ -44,8 +44,9 @@ BookmarksToolbar::BookmarksToolbar(BrowserWindow* window, QWidget* parent)
     setContextMenuPolicy(Qt::CustomContextMenu);
 
     m_layout = new QHBoxLayout(this);
-    m_layout->setMargin(style()->pixelMetric(QStyle::PM_ToolBarItemMargin, 0, this)
-                          + style()->pixelMetric(QStyle::PM_ToolBarFrameWidth, 0, this));
+    auto contentsMargin = style()->pixelMetric(QStyle::PM_ToolBarItemMargin, 0, this)
+                        + style()->pixelMetric(QStyle::PM_ToolBarFrameWidth, 0, this);
+    m_layout->setContentsMargins(contentsMargin, contentsMargin, contentsMargin, contentsMargin);
     m_layout->setSpacing(style()->pixelMetric(QStyle::PM_ToolBarItemSpacing, 0, this));
     setLayout(m_layout);
 
diff --git a/src/lib/bookmarks/bookmarkstoolbarbutton.cpp b/src/lib/bookmarks/bookmarkstoolbarbutton.cpp
index 798970557..8f6c6a016 100644
--- a/src/lib/bookmarks/bookmarkstoolbarbutton.cpp
+++ b/src/lib/bookmarks/bookmarkstoolbarbutton.cpp
@@ -256,7 +256,11 @@ QString BookmarksToolbarButton::createTooltip() const
     return m_bookmark->urlString();
 }
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 void BookmarksToolbarButton::enterEvent(QEvent* event)
+#else
+void BookmarksToolbarButton::enterEvent(QEnterEvent* event)
+#endif
 {
     QPushButton::enterEvent(event);
 
diff --git a/src/lib/bookmarks/bookmarkstoolbarbutton.h b/src/lib/bookmarks/bookmarkstoolbarbutton.h
index 8e34dbd68..13df1e34c 100644
--- a/src/lib/bookmarks/bookmarkstoolbarbutton.h
+++ b/src/lib/bookmarks/bookmarkstoolbarbutton.h
@@ -63,7 +63,11 @@ private:
     void init();
     QString createTooltip() const;
 
-    void enterEvent(QEvent* event) override;
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
+    void enterEvent(QEvent *event) override;
+#else
+    void enterEvent(QEnterEvent *event) override;
+#endif
     void leaveEvent(QEvent* event) override;
     void mousePressEvent(QMouseEvent* event) override;
     void mouseReleaseEvent(QMouseEvent* event) override;
diff --git a/src/lib/downloads/downloaditem.cpp b/src/lib/downloads/downloaditem.cpp
index 381a2e204..7aec65db0 100644
--- a/src/lib/downloads/downloaditem.cpp
+++ b/src/lib/downloads/downloaditem.cpp
@@ -35,7 +35,11 @@
 #include <QMessageBox>
 #include <QFileIconProvider>
 #include <QDesktopServices>
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 #include <QWebEngineDownloadItem>
+#else
+#include <QWebEngineDownloadRequest>
+#endif
 #include <QtWebEngineWidgetsVersion>
 
 #ifdef Q_OS_WIN
@@ -45,7 +49,7 @@
 
 //#define DOWNMANAGER_DEBUG
 
-DownloadItem::DownloadItem(QListWidgetItem *item, QWebEngineDownloadItem* downloadItem, const QString &path, const QString &fileName, bool openFile, DownloadManager* manager)
+DownloadItem::DownloadItem(QListWidgetItem *item, Q_WEB_ENGINE_DOWNLOAD_ITEM_CLASS* downloadItem, const QString &path, const QString &fileName, bool openFile, DownloadManager* manager)
     : QWidget()
     , ui(new Ui::DownloadItem)
     , m_item(item)
@@ -81,11 +85,17 @@ DownloadItem::DownloadItem(QListWidgetItem *item, QWebEngineDownloadItem* downlo
 
 void DownloadItem::startDownloading()
 {
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     connect(m_download, &QWebEngineDownloadItem::finished, this, &DownloadItem::finished);
     connect(m_download, &QWebEngineDownloadItem::downloadProgress, this, &DownloadItem::downloadProgress);
+#else
+    connect(m_download, &QWebEngineDownloadRequest::isFinishedChanged, this, &DownloadItem::finished);
+    connect(m_download, &QWebEngineDownloadRequest::receivedBytesChanged, this, &DownloadItem::receivedOrTotalBytesChanged);
+    connect(m_download, &QWebEngineDownloadRequest::totalBytesChanged, this, &DownloadItem::receivedOrTotalBytesChanged);
+#endif
 
     m_downloading = true;
-    if (m_downTimer.elapsed() < 1) {
+    if (!m_downTimer.isValid()) {
         m_downTimer.start();
     }
 
@@ -123,16 +133,16 @@ void DownloadItem::finished()
     QString host = m_download->url().host();
 
     switch (m_download->state()) {
-    case QWebEngineDownloadItem::DownloadCompleted:
+    case Q_WEB_ENGINE_DOWNLOAD_ITEM_CLASS::DownloadCompleted:
         success = true;
-        ui->downloadInfo->setText(tr("Done - %1 (%2)").arg(host, QDateTime::currentDateTime().toString(Qt::DefaultLocaleShortDate)));
+        ui->downloadInfo->setText(tr("Done - %1 (%2)").arg(host, QLocale().toString(QDateTime::currentDateTime(), QLocale::ShortFormat)));
         break;
 
-    case QWebEngineDownloadItem::DownloadInterrupted:
+    case Q_WEB_ENGINE_DOWNLOAD_ITEM_CLASS::DownloadInterrupted:
         ui->downloadInfo->setText(tr("Error - %1").arg(host));
         break;
 
-    case QWebEngineDownloadItem::DownloadCancelled:
+    case Q_WEB_ENGINE_DOWNLOAD_ITEM_CLASS::DownloadCancelled:
         ui->downloadInfo->setText(tr("Cancelled - %1").arg(host));
         break;
 
@@ -154,8 +164,15 @@ void DownloadItem::finished()
     Q_EMIT downloadFinished(true);
 }
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 void DownloadItem::downloadProgress(qint64 received, qint64 total)
 {
+#else
+void DownloadItem::receivedOrTotalBytesChanged()
+{
+    qint64 received = m_download->receivedBytes();
+    qint64 total = m_download->totalBytes();
+#endif
 #ifdef DOWNMANAGER_DEBUG
     qDebug() << __FUNCTION__ << received << total;
 #endif
diff --git a/src/lib/downloads/downloaditem.h b/src/lib/downloads/downloaditem.h
index 5b53b0c15..b3319c50a 100644
--- a/src/lib/downloads/downloaditem.h
+++ b/src/lib/downloads/downloaditem.h
@@ -25,6 +25,7 @@
 #include <QNetworkReply>
 #include <QElapsedTimer>
 #include <QTime>
+#include <QElapsedTimer>
 
 #include "qzcommon.h"
 
@@ -34,7 +35,13 @@ class DownloadItem;
 }
 
 class QListWidgetItem;
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 class QWebEngineDownloadItem;
+#define Q_WEB_ENGINE_DOWNLOAD_ITEM_CLASS QWebEngineDownloadItem
+#else
+class QWebEngineDownloadRequest;
+#define Q_WEB_ENGINE_DOWNLOAD_ITEM_CLASS QWebEngineDownloadRequest
+#endif
 
 class DownloadManager;
 
@@ -43,7 +50,7 @@ class FALKON_EXPORT DownloadItem : public QWidget
     Q_OBJECT
 
 public:
-    explicit DownloadItem(QListWidgetItem* item, QWebEngineDownloadItem* downloadItem, const QString &path, const QString &fileName, bool openFile, DownloadManager* manager);
+    explicit DownloadItem(QListWidgetItem* item, Q_WEB_ENGINE_DOWNLOAD_ITEM_CLASS* downloadItem, const QString &path, const QString &fileName, bool openFile, DownloadManager* manager);
     bool isDownloading() const { return m_downloading; }
     bool isCancelled();
     QTime remainingTime() const { return m_remTime; }
@@ -68,7 +75,11 @@ Q_SIGNALS:
 private Q_SLOTS:
     void parentResized(const QSize &size);
     void finished();
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     void downloadProgress(qint64 received, qint64 total);
+#else
+    void receivedOrTotalBytesChanged();
+#endif
     void stop();
     void pauseResume();
     void openFile();
@@ -85,7 +96,7 @@ private:
     Ui::DownloadItem* ui;
 
     QListWidgetItem* m_item;
-    QWebEngineDownloadItem* m_download;
+    Q_WEB_ENGINE_DOWNLOAD_ITEM_CLASS* m_download;
     QString m_path;
     QString m_fileName;
     QElapsedTimer m_downTimer;
diff --git a/src/lib/downloads/downloadmanager.cpp b/src/lib/downloads/downloadmanager.cpp
index 2d57a53cb..b9e46db20 100644
--- a/src/lib/downloads/downloadmanager.cpp
+++ b/src/lib/downloads/downloadmanager.cpp
@@ -40,7 +40,11 @@
 #include <QShortcut>
 #include <QStandardPaths>
 #include <QWebEngineHistory>
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 #include <QWebEngineDownloadItem>
+#else
+#include <QWebEngineDownloadRequest>
+#endif
 #include <QtWebEngineWidgetsVersion>
 
 #ifdef Q_OS_WIN
@@ -123,7 +127,11 @@ void DownloadManager::keyPressEvent(QKeyEvent* e)
     QWidget::keyPressEvent(e);
 }
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 void DownloadManager::closeDownloadTab(QWebEngineDownloadItem *item) const
+#else
+void DownloadManager::closeDownloadTab(QWebEngineDownloadRequest *item) const
+#endif
 {
     // Attempt to close empty tab that was opened only for loading the download url
     auto testWebView = [](TabbedWebView *view, const QUrl &url) {
@@ -258,7 +266,7 @@ void DownloadManager::clearList()
     Q_EMIT downloadsCountChanged();
 }
 
-void DownloadManager::download(QWebEngineDownloadItem *downloadItem)
+void DownloadManager::download(Q_WEB_ENGINE_DOWNLOAD_ITEM_CLASS *downloadItem)
 {
     QElapsedTimer downloadTimer;
     downloadTimer.start();
@@ -268,10 +276,14 @@ void DownloadManager::download(QWebEngineDownloadItem *downloadItem)
     QString downloadPath;
     bool openFile = false;
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     const QString fileName = QFileInfo(downloadItem->path()).fileName();
+#else
+    const QString fileName = downloadItem->downloadFileName();
+#endif
 
-    const bool forceAsk = downloadItem->savePageFormat() != QWebEngineDownloadItem::UnknownSaveFormat
-            || downloadItem->type() == QWebEngineDownloadItem::UserRequested;
+    const bool forceAsk = downloadItem->savePageFormat() != Q_WEB_ENGINE_DOWNLOAD_ITEM_CLASS::UnknownSaveFormat
+            || downloadItem->isSavePageDownload();
 
     if (m_useExternalManager) {
         startExternalManager(downloadItem->url());
@@ -279,10 +291,10 @@ void DownloadManager::download(QWebEngineDownloadItem *downloadItem)
         enum Result { Open = 1, Save = 2, ExternalManager = 3, SavePage = 4, Unknown = 0 };
         Result result = Unknown;
 
-        if (downloadItem->savePageFormat() != QWebEngineDownloadItem::UnknownSaveFormat) {
+        if (downloadItem->savePageFormat() != Q_WEB_ENGINE_DOWNLOAD_ITEM_CLASS::UnknownSaveFormat) {
             // Save Page requested
             result = SavePage;
-        } else if (downloadItem->type() == QWebEngineDownloadItem::UserRequested) {
+        } else if (downloadItem->isSavePageDownload()) {
             // Save x as... requested
             result = Save;
         } else {
@@ -326,17 +338,17 @@ void DownloadManager::download(QWebEngineDownloadItem *downloadItem)
                 Settings().setValue(QSL("DownloadManager/lastDownloadPath"), m_lastDownloadPath);
                 m_lastDownloadOption = SaveFile;
 
-                QWebEngineDownloadItem::SavePageFormat format = QWebEngineDownloadItem::UnknownSaveFormat;
+                Q_WEB_ENGINE_DOWNLOAD_ITEM_CLASS::SavePageFormat format = Q_WEB_ENGINE_DOWNLOAD_ITEM_CLASS::UnknownSaveFormat;
 
                 if (selectedFilter == mhtml) {
-                    format = QWebEngineDownloadItem::MimeHtmlSaveFormat;
+                    format = Q_WEB_ENGINE_DOWNLOAD_ITEM_CLASS::MimeHtmlSaveFormat;
                 } else if (selectedFilter == htmlSingle) {
-                    format = QWebEngineDownloadItem::SingleHtmlSaveFormat;
+                    format = Q_WEB_ENGINE_DOWNLOAD_ITEM_CLASS::SingleHtmlSaveFormat;
                 } else if (selectedFilter == htmlComplete) {
-                    format = QWebEngineDownloadItem::CompleteHtmlSaveFormat;
+                    format = Q_WEB_ENGINE_DOWNLOAD_ITEM_CLASS::CompleteHtmlSaveFormat;
                 }
 
-                if (format != QWebEngineDownloadItem::UnknownSaveFormat) {
+                if (format != Q_WEB_ENGINE_DOWNLOAD_ITEM_CLASS::UnknownSaveFormat) {
                     downloadItem->setSavePageFormat(format);
                 }
             }
@@ -361,7 +373,12 @@ void DownloadManager::download(QWebEngineDownloadItem *downloadItem)
     }
 
     // Set download path and accept
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     downloadItem->setPath(downloadPath);
+#else
+    downloadItem->setDownloadDirectory(QFileInfo(downloadPath).absoluteDir().absolutePath());
+    downloadItem->setDownloadFileName(QFileInfo(downloadPath).fileName());
+#endif
     downloadItem->accept();
 
     // Create download item
diff --git a/src/lib/downloads/downloadmanager.h b/src/lib/downloads/downloadmanager.h
index ec4900f52..d53d0cd39 100644
--- a/src/lib/downloads/downloadmanager.h
+++ b/src/lib/downloads/downloadmanager.h
@@ -32,7 +32,11 @@ class DownloadManager;
 class QUrl;
 class QNetworkAccessManager;
 class QListWidgetItem;
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 class QWebEngineDownloadItem;
+#else
+class QWebEngineDownloadRequest;
+#endif
 class QWinTaskbarButton;
 
 class DownloadItem;
@@ -65,7 +69,11 @@ public:
 
     void loadSettings();
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     void download(QWebEngineDownloadItem *downloadItem);
+#else
+    void download(QWebEngineDownloadRequest *downloadItem);
+#endif
 
     int downloadsCount() const;
     int activeDownloadsCount() const;
@@ -98,7 +106,11 @@ private:
     void resizeEvent(QResizeEvent* e) override;
     void keyPressEvent(QKeyEvent* e) override;
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     void closeDownloadTab(QWebEngineDownloadItem *item) const;
+#else
+    void closeDownloadTab(QWebEngineDownloadRequest *item) const;
+#endif
     QWinTaskbarButton *taskbarButton();
 
     Ui::DownloadManager* ui;
diff --git a/src/lib/downloads/downloadoptionsdialog.cpp b/src/lib/downloads/downloadoptionsdialog.cpp
index 3704581f1..18f20a776 100644
--- a/src/lib/downloads/downloadoptionsdialog.cpp
+++ b/src/lib/downloads/downloadoptionsdialog.cpp
@@ -21,9 +21,13 @@
 
 #include <QClipboard>
 #include <QMimeDatabase>
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 #include <QWebEngineDownloadItem>
+#else
+#include <QWebEngineDownloadRequest>
+#endif
 
-DownloadOptionsDialog::DownloadOptionsDialog(const QString &fileName, QWebEngineDownloadItem *downloadItem, QWidget *parent)
+DownloadOptionsDialog::DownloadOptionsDialog(const QString &fileName, Q_WEB_ENGINE_DOWNLOAD_ITEM_CLASS *downloadItem, QWidget *parent)
     : QDialog(parent)
     , ui(new Ui::DownloadOptionsDialog)
     , m_downloadItem(downloadItem)
diff --git a/src/lib/downloads/downloadoptionsdialog.h b/src/lib/downloads/downloadoptionsdialog.h
index 614598bb9..aabddd1e6 100644
--- a/src/lib/downloads/downloadoptionsdialog.h
+++ b/src/lib/downloads/downloadoptionsdialog.h
@@ -23,20 +23,25 @@
 
 #include "qzcommon.h"
 #include "downloadmanager.h"
+#include "downloaditem.h"
 
 namespace Ui
 {
 class DownloadOptionsDialog;
 }
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 class QWebEngineDownloadItem;
+#else
+class QWebEngineDownloadRequest;
+#endif
 
 class FALKON_EXPORT DownloadOptionsDialog : public QDialog
 {
     Q_OBJECT
 
 public:
-    explicit DownloadOptionsDialog(const QString &fileName, QWebEngineDownloadItem *downloadItem, QWidget* parent = nullptr);
+    explicit DownloadOptionsDialog(const QString &fileName, Q_WEB_ENGINE_DOWNLOAD_ITEM_CLASS *downloadItem, QWidget* parent = nullptr);
     ~DownloadOptionsDialog() override;
 
     void showExternalManagerOption(bool show);
@@ -56,7 +61,7 @@ Q_SIGNALS:
 private:
     Ui::DownloadOptionsDialog* ui;
 
-    QWebEngineDownloadItem *m_downloadItem;
+    Q_WEB_ENGINE_DOWNLOAD_ITEM_CLASS *m_downloadItem;
     bool m_signalEmited;
 };
 
diff --git a/src/lib/history/historymenu.cpp b/src/lib/history/historymenu.cpp
index 0702bce8a..ec82561fc 100644
--- a/src/lib/history/historymenu.cpp
+++ b/src/lib/history/historymenu.cpp
@@ -242,10 +242,10 @@ void HistoryMenu::init()
     act->setShortcut(QzTools::actionShortcut(QKeySequence::Forward, Qt::ALT + Qt::Key_Right, QKeySequence::Back, Qt::ALT + Qt::Key_Left));
 
     act = addAction(QIcon::fromTheme("go-home"), tr("&Home"), this, &HistoryMenu::goHome);
-    act->setShortcut(QKeySequence(Qt::ALT + Qt::Key_Home));
+    act->setShortcut(QKeySequence(Qt::ALT | Qt::Key_Home));
 
     act = addAction(QIcon::fromTheme("deep-history", QIcon(":/icons/menu/history.svg")), tr("Show &All History"), this, &HistoryMenu::showHistoryManager);
-    act->setShortcut(QKeySequence(Qt::CTRL + Qt::SHIFT + Qt::Key_H));
+    act->setShortcut(QKeySequence(Qt::CTRL | Qt::SHIFT | Qt::Key_H));
 
     addSeparator();
 
diff --git a/src/lib/navigation/completer/locationcompleterdelegate.cpp b/src/lib/navigation/completer/locationcompleterdelegate.cpp
index f4c9dde93..1add6fa7f 100644
--- a/src/lib/navigation/completer/locationcompleterdelegate.cpp
+++ b/src/lib/navigation/completer/locationcompleterdelegate.cpp
@@ -324,7 +324,11 @@ int LocationCompleterDelegate::viewItemDrawText(QPainter *p, const QStyleOptionV
                 highlightParts << highlightedPart;
             }
 
-            textLayout.setAdditionalFormats(highlightParts);
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
+            textLayout.setFormats(QVector<QTextLayout::FormatRange>::fromList(highlightParts));
+#else
+            textLayout.setFormats(highlightParts);
+#endif
         }
     }
 
diff --git a/src/lib/navigation/completer/locationcompleterrefreshjob.cpp b/src/lib/navigation/completer/locationcompleterrefreshjob.cpp
index 90b801999..ab07db190 100644
--- a/src/lib/navigation/completer/locationcompleterrefreshjob.cpp
+++ b/src/lib/navigation/completer/locationcompleterrefreshjob.cpp
@@ -40,7 +40,11 @@ LocationCompleterRefreshJob::LocationCompleterRefreshJob(const QString &searchSt
     m_watcher = new QFutureWatcher<void>(this);
     connect(m_watcher, &QFutureWatcherBase::finished, this, &LocationCompleterRefreshJob::slotFinished);
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     QFuture<void> future = QtConcurrent::run(this, &LocationCompleterRefreshJob::runJob);
+#else
+    QFuture<void> future = QtConcurrent::run(&LocationCompleterRefreshJob::runJob, this);
+#endif
     m_watcher->setFuture(future);
 }
 
diff --git a/src/lib/navigation/locationbar.cpp b/src/lib/navigation/locationbar.cpp
index fadd2b3d3..656244935 100644
--- a/src/lib/navigation/locationbar.cpp
+++ b/src/lib/navigation/locationbar.cpp
@@ -41,7 +41,7 @@
 #include <QCompleter>
 #include <QStringListModel>
 #include <QContextMenuEvent>
-#include <QStyleOptionFrameV3>
+#include <QStyleOptionFrame>
 
 LocationBar::LocationBar(QWidget *parent)
     : LineEdit(parent)
diff --git a/src/lib/navigation/navigationbar.cpp b/src/lib/navigation/navigationbar.cpp
index 4127ae8ab..1612a5b9a 100644
--- a/src/lib/navigation/navigationbar.cpp
+++ b/src/lib/navigation/navigationbar.cpp
@@ -66,8 +66,9 @@ NavigationBar::NavigationBar(BrowserWindow* window)
     setObjectName(QSL("navigationbar"));
 
     m_layout = new QHBoxLayout(this);
-    m_layout->setMargin(style()->pixelMetric(QStyle::PM_ToolBarItemMargin, 0, this)
-                          + style()->pixelMetric(QStyle::PM_ToolBarFrameWidth, 0, this));
+    auto contentsMargin = style()->pixelMetric(QStyle::PM_ToolBarItemMargin, 0, this)
+                        + style()->pixelMetric(QStyle::PM_ToolBarFrameWidth, 0, this);
+    m_layout->setContentsMargins(contentsMargin, contentsMargin, contentsMargin, contentsMargin);
     m_layout->setSpacing(style()->pixelMetric(QStyle::PM_ToolBarItemSpacing, 0, this));
     setLayout(m_layout);
 
@@ -281,12 +282,13 @@ void NavigationBar::setSuperMenuVisible(bool visible)
 
 int NavigationBar::layoutMargin() const
 {
-    return m_layout->margin();
+    // NOTE: This assumes margins are always the same.
+    return m_layout->contentsMargins().left();
 }
 
 void NavigationBar::setLayoutMargin(int margin)
 {
-    m_layout->setMargin(margin);
+    m_layout->setContentsMargins(margin, margin, margin, margin);
 }
 
 int NavigationBar::layoutSpacing() const
diff --git a/src/lib/navigation/websearchbar.cpp b/src/lib/navigation/websearchbar.cpp
index 13aaf80e0..5533ff44f 100644
--- a/src/lib/navigation/websearchbar.cpp
+++ b/src/lib/navigation/websearchbar.cpp
@@ -178,7 +178,11 @@ void WebSearchBar::setupEngines()
         item.icon = en.icon;
         item.text = en.name;
         QVariant v;
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
         v.setValue<SearchEngine>(en);
+#else
+        v.setValue(en);
+#endif
         item.userData = v;
 
         m_boxSearchType->addItem(item);
diff --git a/src/lib/network/networkmanager.cpp b/src/lib/network/networkmanager.cpp
index 47dff865d..92fe858b5 100644
--- a/src/lib/network/networkmanager.cpp
+++ b/src/lib/network/networkmanager.cpp
@@ -70,24 +70,45 @@ NetworkManager::NetworkManager(QObject *parent)
     });
 }
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 bool NetworkManager::certificateError(const QWebEngineCertificateError &error, QWidget *parent)
+#else
+bool NetworkManager::certificateError(QWebEngineCertificateError &error, QWidget *parent)
+#endif
 {
     const QString &host = error.url().host();
 
-    if (m_rejectedSslErrors.contains(host) && m_rejectedSslErrors.value(host) == error.error()) {
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
+    const auto errorType = error.error();
+#else
+    const auto errorType = error.type();
+#endif
+
+    if (m_rejectedSslErrors.contains(host) && m_rejectedSslErrors.value(host) == errorType) {
         return false;
     }
 
-    if ((m_ignoredSslErrors.contains(host) && m_ignoredSslErrors.value(host) == error.error())
+    if ((m_ignoredSslErrors.contains(host) && m_ignoredSslErrors.value(host) == errorType)
             || m_ignoredSslHosts.contains(host)) {
         return true;
     }
 
+#if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
+    // Defer loading the URL until the user prompt has completed.
+    if (error.isOverridable())
+        error.defer();
+#endif
+
     QString title = tr("SSL Certificate Error!");
     QString text1 = tr("The page you are trying to access has the following errors in the SSL certificate:");
     QString text2 = tr("Would you like to make an exception for this certificate?");
 
-    QString message = QSL("<b>%1</b><p>%2</p><ul><li>%3</li></ul><p>%4</p>").arg(title, text1, error.errorDescription(), text2);
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
+    const auto errorDescription = error.errorDescription();
+#else
+    const auto errorDescription = error.description();
+#endif
+    QString message = QSL("<b>%1</b><p>%2</p><ul><li>%3</li></ul><p>%4</p>").arg(title, text1, errorDescription, text2);
 
     SslErrorDialog dialog(parent);
     dialog.setText(message);
@@ -100,11 +121,11 @@ bool NetworkManager::certificateError(const QWebEngineCertificateError &error, Q
         return true;
 
     case SslErrorDialog::OnlyForThisSession:
-        m_ignoredSslErrors[host] = error.error();
+        m_ignoredSslErrors[host] = errorType;
         return true;
 
     case SslErrorDialog::NoForThisSession:
-        m_rejectedSslErrors[host] = error.error();
+        m_rejectedSslErrors[host] = errorType;
         return false;
 
     default:
@@ -329,8 +350,11 @@ void NetworkManager::registerSchemes()
 QNetworkReply *NetworkManager::createRequest(QNetworkAccessManager::Operation op, const QNetworkRequest &request, QIODevice *outgoingData)
 {
     QNetworkRequest req = request;
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
+    // These have either been removed or changed to the default in Qt 6.
     req.setAttribute(QNetworkRequest::SpdyAllowedAttribute, true);
     req.setAttribute(QNetworkRequest::FollowRedirectsAttribute, true);
+#endif
 
     return QNetworkAccessManager::createRequest(op, req, outgoingData);
 }
diff --git a/src/lib/network/networkmanager.h b/src/lib/network/networkmanager.h
index 3267bfe31..ff2d9a745 100644
--- a/src/lib/network/networkmanager.h
+++ b/src/lib/network/networkmanager.h
@@ -35,7 +35,11 @@ class FALKON_EXPORT NetworkManager : public QNetworkAccessManager
 public:
     explicit NetworkManager(QObject *parent = nullptr);
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     bool certificateError(const QWebEngineCertificateError &error, QWidget *parent = nullptr);
+#else
+    bool certificateError(QWebEngineCertificateError &error, QWidget *parent = nullptr);
+#endif
     void authentication(const QUrl &url, QAuthenticator *auth, QWidget *parent = nullptr);
     void proxyAuthentication(const QString &proxyHost, QAuthenticator *auth, QWidget *parent = nullptr);
 
@@ -58,8 +62,13 @@ private:
 
     NetworkUrlInterceptor *m_urlInterceptor;
     ExtensionSchemeManager *m_extensionScheme;
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     QHash<QString, QWebEngineCertificateError::Error> m_ignoredSslErrors;
     QHash<QString, QWebEngineCertificateError::Error> m_rejectedSslErrors;
+#else
+    QHash<QString, QWebEngineCertificateError::Type> m_ignoredSslErrors;
+    QHash<QString, QWebEngineCertificateError::Type> m_rejectedSslErrors;
+#endif
     QStringList m_ignoredSslHosts;
 };
 
diff --git a/src/lib/opensearch/editsearchengine.cpp b/src/lib/opensearch/editsearchengine.cpp
index 25a5683a2..ad1b684a3 100644
--- a/src/lib/opensearch/editsearchengine.cpp
+++ b/src/lib/opensearch/editsearchengine.cpp
@@ -81,7 +81,11 @@ void EditSearchEngine::setShortcut(const QString &shortcut)
 
 QIcon EditSearchEngine::icon()
 {
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     return QIcon(*ui->icon->pixmap());
+#else
+    return QIcon(ui->icon->pixmap());
+#endif
 }
 
 void EditSearchEngine::setIcon(const QIcon &icon)
diff --git a/src/lib/opensearch/searchenginesdialog.cpp b/src/lib/opensearch/searchenginesdialog.cpp
index 743eed5e8..d5bd756b2 100644
--- a/src/lib/opensearch/searchenginesdialog.cpp
+++ b/src/lib/opensearch/searchenginesdialog.cpp
@@ -173,7 +173,11 @@ SearchEngine SearchEnginesDialog::getEngine(QTreeWidgetItem* item)
 void SearchEnginesDialog::setEngine(QTreeWidgetItem* item, const SearchEngine &engine)
 {
     QVariant v;
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     v.setValue<SearchEngine>(engine);
+#else
+    v.setValue(engine);
+#endif
     item->setData(0, EngineRole, v);
     item->setText(0, engine.name);
 }
diff --git a/src/lib/other/statusbar.cpp b/src/lib/other/statusbar.cpp
index 5f7a12710..b89a118ef 100644
--- a/src/lib/other/statusbar.cpp
+++ b/src/lib/other/statusbar.cpp
@@ -138,7 +138,7 @@ void TipLabel::paintEvent(QPaintEvent* ev)
 {
     QStylePainter p(this);
     QStyleOptionFrame opt;
-    opt.init(this);
+    opt.initFrom(this);
     p.drawPrimitive(QStyle::PE_PanelTipLabel, opt);
     p.end();
 
diff --git a/src/lib/plugins/ocssupport.cpp b/src/lib/plugins/ocssupport.cpp
index 019d076d0..d153620e5 100644
--- a/src/lib/plugins/ocssupport.cpp
+++ b/src/lib/plugins/ocssupport.cpp
@@ -28,7 +28,11 @@
 #include <QUrlQuery>
 #include <QNetworkReply>
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 #include <KArchive/KZip>
+#else
+#include <KZip>
+#endif
 
 Q_GLOBAL_STATIC(OcsSupport, qz_ocs_support)
 
diff --git a/src/lib/plugins/plugins.cpp b/src/lib/plugins/plugins.cpp
index 702334f21..ff2fff350 100644
--- a/src/lib/plugins/plugins.cpp
+++ b/src/lib/plugins/plugins.cpp
@@ -342,7 +342,7 @@ Plugins::Plugin Plugins::loadPlugin(const QString &id)
 
     const int colon = id.indexOf(QL1C(':'));
     if (colon > -1) {
-        const auto t = id.leftRef(colon);
+        const auto t = QStringView{id}.left(colon);
         if (t == QL1S("internal")) {
             type = Plugin::InternalPlugin;
         } else if (t == QL1S("lib")) {
diff --git a/src/lib/plugins/plugins.h b/src/lib/plugins/plugins.h
index 00fef0d51..556960eef 100644
--- a/src/lib/plugins/plugins.h
+++ b/src/lib/plugins/plugins.h
@@ -21,6 +21,7 @@
 #include <QObject>
 #include <QVariant>
 #include <QPointer>
+#include <QPixmap>
 
 #include "qzcommon.h"
 #include "plugininterface.h"
diff --git a/src/lib/plugins/qml/api/bookmarks/qmlbookmarktreenode.h b/src/lib/plugins/qml/api/bookmarks/qmlbookmarktreenode.h
index b9cc01421..f0c6dfefb 100644
--- a/src/lib/plugins/qml/api/bookmarks/qmlbookmarktreenode.h
+++ b/src/lib/plugins/qml/api/bookmarks/qmlbookmarktreenode.h
@@ -18,6 +18,8 @@
 #pragma once
 #include "bookmarkitem.h"
 
+#include <QObject>
+
 /**
  * @brief The class exposing the bookmark item to QML
  */
diff --git a/src/lib/plugins/qml/api/events/qmlwheelevent.cpp b/src/lib/plugins/qml/api/events/qmlwheelevent.cpp
index ec3389759..dfa3dfba7 100644
--- a/src/lib/plugins/qml/api/events/qmlwheelevent.cpp
+++ b/src/lib/plugins/qml/api/events/qmlwheelevent.cpp
@@ -69,7 +69,7 @@ int QmlWheelEvent::globalY() const
     if (!m_wheelEvent) {
         return -1;
     }
-    return m_wheelEvent->globalPosition().toPoint().x();
+    return m_wheelEvent->globalPosition().toPoint().y();
 }
 
 bool QmlWheelEvent::inverted() const
diff --git a/src/lib/plugins/qml/api/userscript/qmluserscript.cpp b/src/lib/plugins/qml/api/userscript/qmluserscript.cpp
index 3f3b1deb7..2638a368a 100644
--- a/src/lib/plugins/qml/api/userscript/qmluserscript.cpp
+++ b/src/lib/plugins/qml/api/userscript/qmluserscript.cpp
@@ -20,6 +20,9 @@
 
 QmlUserScript::QmlUserScript(QObject *parent)
     : QObject(parent)
+#if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
+    , m_isNull(true)
+#endif
 {
 }
 
@@ -35,12 +38,17 @@ QWebEngineScript QmlUserScript::webEngineScript() const
 
 void QmlUserScript::setWebEngineScript(const QWebEngineScript &script)
 {
+    setNotNull();
     m_webEngineScript = script;
 }
 
 bool QmlUserScript::null() const
 {
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     return m_webEngineScript.isNull();
+#else
+    return m_isNull;
+#endif
 }
 
 QString QmlUserScript::name() const
@@ -50,6 +58,7 @@ QString QmlUserScript::name() const
 
 void QmlUserScript::setName(const QString &name)
 {
+    setNotNull();
     m_webEngineScript.setName(name);
     Q_EMIT nameChanged(name);
     aboutToUpdateUnderlyingScript();
@@ -62,6 +71,7 @@ bool QmlUserScript::runsOnSubFrames() const
 
 void QmlUserScript::setRunsOnSubFrames(bool runsOnSubFrames)
 {
+    setNotNull();
     m_webEngineScript.setRunsOnSubFrames(runsOnSubFrames);
     Q_EMIT runsOnSubFramesChanged(runsOnSubFrames);
     aboutToUpdateUnderlyingScript();
@@ -74,6 +84,7 @@ int QmlUserScript::worldId() const
 
 void QmlUserScript::setWorldId(int worldId)
 {
+    setNotNull();
     switch (worldId) {
     case QWebEngineScript::MainWorld:
         m_webEngineScript.setWorldId(QWebEngineScript::MainWorld);
@@ -98,6 +109,7 @@ QString QmlUserScript::sourceCode() const
 
 void QmlUserScript::setSourceCode(const QString &sourceCode)
 {
+    setNotNull();
     m_webEngineScript.setSourceCode(sourceCode);
     Q_EMIT sourceCodeChanged(sourceCode);
     aboutToUpdateUnderlyingScript();
@@ -110,6 +122,7 @@ QmlUserScript::InjectionPoint QmlUserScript::injectionPoint() const
 
 void QmlUserScript::setInjectionPoint(InjectionPoint injectionPoint)
 {
+    setNotNull();
     switch (static_cast<QWebEngineScript::InjectionPoint>(injectionPoint)) {
     case QWebEngineScript::DocumentCreation:
         m_webEngineScript.setInjectionPoint(QWebEngineScript::DocumentCreation);
diff --git a/src/lib/plugins/qml/api/userscript/qmluserscript.h b/src/lib/plugins/qml/api/userscript/qmluserscript.h
index c8c00164d..bd1a5c668 100644
--- a/src/lib/plugins/qml/api/userscript/qmluserscript.h
+++ b/src/lib/plugins/qml/api/userscript/qmluserscript.h
@@ -100,6 +100,9 @@ Q_SIGNALS:
     void injectionPointChanged(int injectionPoint);
 private:
     QWebEngineScript m_webEngineScript;
+#if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
+    bool m_isNull;
+#endif
     QBasicTimer m_basicTimer;
 
     bool null() const;
@@ -116,4 +119,12 @@ private:
 
     void timerEvent(QTimerEvent *e) override;
     void aboutToUpdateUnderlyingScript();
+
+    void setNotNull()
+    {
+#if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
+        // TODO: This is a really hacky way of keeping track of whether the script has been initialized - and is it even necessary?
+        m_isNull = false;
+#endif
+    }
 };
diff --git a/src/lib/plugins/qml/api/userscript/qmluserscripts.cpp b/src/lib/plugins/qml/api/userscript/qmluserscripts.cpp
index 9ff176519..1fa2bf1fc 100644
--- a/src/lib/plugins/qml/api/userscript/qmluserscripts.cpp
+++ b/src/lib/plugins/qml/api/userscript/qmluserscripts.cpp
@@ -33,7 +33,7 @@ int QmlUserScripts::count() const
 
 int QmlUserScripts::size() const
 {
-    return mApp->webProfile()->scripts()->size();
+    return mApp->webProfile()->scripts()->count();
 }
 
 bool QmlUserScripts::empty() const
@@ -65,15 +65,28 @@ bool QmlUserScripts::contains(QObject *object) const
 
 QObject *QmlUserScripts::findScript(const QString &name) const
 {
-    QWebEngineScript webEngineScript = mApp->webProfile()->scripts()->findScript(name);
     auto *qmlUserScript = new QmlUserScript();
+
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
+    QWebEngineScript webEngineScript = mApp->webProfile()->scripts()->findScript(name);
     qmlUserScript->setWebEngineScript(webEngineScript);
+#else
+    auto scripts = mApp->webProfile()->scripts()->find(name);
+    if (!scripts.empty()) {
+        qmlUserScript->setWebEngineScript(scripts.first());
+    }
+#endif
+
     return qmlUserScript;
 }
 
 QList<QObject*> QmlUserScripts::findScripts(const QString &name) const
 {
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     QList<QWebEngineScript> list = mApp->webProfile()->scripts()->findScripts(name);
+#else
+    QList<QWebEngineScript> list = mApp->webProfile()->scripts()->find(name);
+#endif
     return toQObjectList(list);
 }
 
diff --git a/src/lib/plugins/speeddial.h b/src/lib/plugins/speeddial.h
index e00e11587..a8e9c5802 100644
--- a/src/lib/plugins/speeddial.h
+++ b/src/lib/plugins/speeddial.h
@@ -42,7 +42,7 @@ public:
             return !url.isEmpty();
         }
 
-        bool operator==(const Page &other) {
+        bool operator==(const Page &other) const {
             return (this->title == other.title &&
                     this->url == other.url);
         }
diff --git a/src/lib/preferences/autofillmanager.cpp b/src/lib/preferences/autofillmanager.cpp
index 59c9ce632..3f3188e1f 100644
--- a/src/lib/preferences/autofillmanager.cpp
+++ b/src/lib/preferences/autofillmanager.cpp
@@ -92,7 +92,11 @@ void AutoFillManager::loadPasswords()
         item->setText(2, "*****");
 
         QVariant v;
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
         v.setValue<PasswordEntry>(entry);
+#else
+        v.setValue(entry);
+#endif
         item->setData(0, Qt::UserRole + 10, v);
         ui->treePass->addTopLevelItem(item);
     }
@@ -253,12 +257,17 @@ void AutoFillManager::editPass()
 
     if (ok && !text.isEmpty() && text != entry.password) {
         QByteArray oldPass = "=" + PasswordManager::urlEncodePassword(entry.password);
-        entry.data.replace(oldPass, "=" + PasswordManager::urlEncodePassword(text));
+        QByteArray newPass = "=" + PasswordManager::urlEncodePassword(text);
+        entry.data.replace(oldPass, newPass);
         entry.password = text;
 
         if (mApp->autoFill()->updateEntry(entry)) {
             QVariant v;
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
             v.setValue<PasswordEntry>(entry);
+#else
+            v.setValue(entry);
+#endif
             curItem->setData(0, Qt::UserRole + 10, v);
 
             if (m_passwordsShown) {
diff --git a/src/lib/preferences/pluginlistdelegate.cpp b/src/lib/preferences/pluginlistdelegate.cpp
index 80e1e77a3..09bbad9f0 100644
--- a/src/lib/preferences/pluginlistdelegate.cpp
+++ b/src/lib/preferences/pluginlistdelegate.cpp
@@ -72,9 +72,9 @@ void PluginListDelegate::paint(QPainter* painter, const QStyleOptionViewItem &op
     const int checkboxYPos = center - (checkboxSize / 2);
     QStyleOptionViewItem opt2 = opt;
     opt2.checkState == Qt::Checked ? opt2.state |= QStyle::State_On : opt2.state |= QStyle::State_Off;
-    QRect styleCheckBoxRect = style->subElementRect(QStyle::SE_ViewItemCheckIndicator, &opt2, w);
+    QRect styleCheckBoxRect = style->subElementRect(QStyle::SE_ItemViewItemCheckIndicator, &opt2, w);
     opt2.rect = QRect(leftPosition, checkboxYPos, styleCheckBoxRect.width(), styleCheckBoxRect.height());
-    style->drawPrimitive(QStyle::PE_IndicatorViewItemCheck, &opt2, painter, w);
+    style->drawPrimitive(QStyle::PE_IndicatorItemViewItemCheck, &opt2, painter, w);
     leftPosition = opt2.rect.right() + m_padding;
 
     // Draw icon
diff --git a/src/lib/preferences/preferences.cpp b/src/lib/preferences/preferences.cpp
index 0e8771724..6eebc2724 100644
--- a/src/lib/preferences/preferences.cpp
+++ b/src/lib/preferences/preferences.cpp
@@ -57,7 +57,9 @@
 #include <QMessageBox>
 #include <QCloseEvent>
 #include <QColorDialog>
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 #include <QDesktopWidget>
+#endif
 #include <QWebEngineProfile>
 #include <QWebEngineSettings>
 #include <QLibraryInfo>
@@ -530,13 +532,17 @@ Preferences::Preferences(BrowserWindow* window)
 
     ui->listWidget->setCurrentRow(currentSettingsPage);
 
-    QDesktopWidget* desktop = QApplication::desktop();
     QSize s = size();
-    if (desktop->availableGeometry(this).size().width() < s.width()) {
-        s.setWidth(desktop->availableGeometry(this).size().width() - 50);
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
+    const QRect &availableGeometryForScreen = QApplication::desktop()->availableGeometry(this);
+#else
+    const QRect &availableGeometryForScreen = screen()->availableGeometry();
+#endif
+    if (availableGeometryForScreen.size().width() < s.width()) {
+        s.setWidth(availableGeometryForScreen.size().width() - 50);
     }
-    if (desktop->availableGeometry(this).size().height() < s.height()) {
-        s.setHeight(desktop->availableGeometry(this).size().height() - 50);
+    if (availableGeometryForScreen.size().height() < s.height()) {
+        s.setHeight(availableGeometryForScreen.size().height() - 50);
     }
     resize(s);
 
diff --git a/src/lib/session/sessionmanager.cpp b/src/lib/session/sessionmanager.cpp
index 476c0cea5..b4a015f4f 100644
--- a/src/lib/session/sessionmanager.cpp
+++ b/src/lib/session/sessionmanager.cpp
@@ -25,6 +25,7 @@
 #include "settings.h"
 
 #include <QAction>
+#include <QActionGroup>
 #include <QComboBox>
 #include <QDateTime>
 #include <QDialogButtonBox>
diff --git a/src/lib/session/sessionmanagerdialog.cpp b/src/lib/session/sessionmanagerdialog.cpp
index 3d09c58d0..4a9cd511b 100644
--- a/src/lib/session/sessionmanagerdialog.cpp
+++ b/src/lib/session/sessionmanagerdialog.cpp
@@ -114,7 +114,7 @@ void SessionManagerDialog::refresh()
     for (const auto &session : sessions) {
         auto *item = new QTreeWidgetItem;
         item->setText(0, session.name);
-        item->setText(1, QFileInfo(session.filePath).lastModified().toString(Qt::DefaultLocaleShortDate));
+        item->setText(1, QLocale().toString(QFileInfo(session.filePath).lastModified(), QLocale::ShortFormat));
         item->setData(0, SessionFileRole, session.filePath);
         item->setData(0, IsBackupSessionRole, session.isBackup);
         item->setData(0, IsActiveSessionRole, session.isActive);
diff --git a/src/lib/sidebar/sidebar.cpp b/src/lib/sidebar/sidebar.cpp
index dad51a4e2..0c023fe54 100644
--- a/src/lib/sidebar/sidebar.cpp
+++ b/src/lib/sidebar/sidebar.cpp
@@ -25,6 +25,7 @@
 #include "settings.h"
 
 #include <QMenu>
+#include <QActionGroup>
 
 QHash<QString, QPointer<SideBarInterface> > s_sidebars;
 
diff --git a/src/lib/tabwidget/combotabbar.cpp b/src/lib/tabwidget/combotabbar.cpp
index 4be0c3c1d..07aed64e2 100644
--- a/src/lib/tabwidget/combotabbar.cpp
+++ b/src/lib/tabwidget/combotabbar.cpp
@@ -27,8 +27,8 @@
 #include <QIcon>
 #include <QHBoxLayout>
 #include <QStylePainter>
-#include <QStyleOptionTabV3>
-#include <QStyleOptionTabBarBaseV2>
+#include <QStyleOptionTab>
+#include <QStyleOptionTabBarBase>
 #include <QPropertyAnimation>
 #include <QScrollArea>
 #include <QTimer>
@@ -682,7 +682,7 @@ void ComboTabBar::paintEvent(QPaintEvent* ev)
 
     // This is needed to apply style sheets
     QStyleOption option;
-    option.init(this);
+    option.initFrom(this);
     QPainter p(this);
     style()->drawPrimitive(QStyle::PE_Widget, &option, &p, this);
 
@@ -1230,7 +1230,7 @@ void TabBarHelper::initStyleBaseOption(QStyleOptionTabBarBase *optTabBase, QTabB
     tabOverlap.shape = tabbar->shape();
     int overlap = tabbar->style()->pixelMetric(QStyle::PM_TabBarBaseOverlap, &tabOverlap, tabbar);
     QWidget* theParent = tabbar->parentWidget();
-    optTabBase->init(tabbar);
+    optTabBase->initFrom(tabbar);
     optTabBase->shape = tabbar->shape();
     optTabBase->documentMode = tabbar->documentMode();
     if (theParent && overlap > 0) {
@@ -1359,7 +1359,9 @@ void TabBarHelper::paintEvent(QPaintEvent *)
             grabImage.setDevicePixelRatio(devicePixelRatioF());
             grabImage.fill(Qt::transparent);
             QStylePainter p(&grabImage, this);
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
             p.initFrom(this);
+#endif
             if (tabDragOffset != 0) {
                 tab.position = QStyleOptionTab::OnlyOneTab;
             }
@@ -1537,7 +1539,7 @@ TabBarScrollWidget::TabBarScrollWidget(QTabBar* tabBar, QWidget* parent)
     : QWidget(parent)
     , m_tabBar(tabBar)
     , m_usesScrollButtons(false)
-    , m_totalDeltas(0)
+    , m_totalVerticalDeltas(0)
 {
     m_scrollArea = new QScrollArea(this);
     m_scrollArea->setFocusPolicy(Qt::NoFocus);
@@ -1696,30 +1698,33 @@ void TabBarScrollWidget::scrollByWheel(QWheelEvent* event)
 {
     event->accept();
 
-    // Check if direction has changed from last time
-    if (m_totalDeltas * event->delta() < 0) {
-        m_totalDeltas = 0;
+    // Process horizontal wheel scrolling first
+    // Slower scrolling for horizontal wheel scrolling
+    if (event->angleDelta().x() > 0) {
+        scrollToLeft();
+    }
+    else if (event->angleDelta().x() < 0) {
+        scrollToRight();
     }
 
-    m_totalDeltas += event->delta();
-
-    // Slower scrolling for horizontal wheel scrolling
-    if (event->orientation() == Qt::Horizontal) {
-        if (event->delta() > 0) {
-            scrollToLeft();
-        }
-        else if (event->delta() < 0) {
-            scrollToRight();
-        }
+    auto verticalDelta = event->angleDelta().y();
+    if (verticalDelta == 0) {
         return;
     }
 
+    // Check if vertical direction has changed from last time
+    if (m_totalVerticalDeltas * verticalDelta < 0) {
+        m_totalVerticalDeltas = 0;
+    }
+
+    m_totalVerticalDeltas += verticalDelta;
+
     // Faster scrolling with control modifier
-    if (event->orientation() == Qt::Vertical && event->modifiers() == Qt::ControlModifier) {
-        if (event->delta() > 0) {
+    if (event->modifiers() == Qt::ControlModifier) {
+        if (verticalDelta > 0) {
             scrollToLeft(10);
         }
-        else if (event->delta() < 0) {
+        else if (verticalDelta < 0) {
             scrollToRight(10);
         }
         return;
@@ -1731,7 +1736,7 @@ void TabBarScrollWidget::scrollByWheel(QWheelEvent* event)
         factor = m_scrollBar->pageStep();
     }
 
-    int offset = (m_totalDeltas / 120) * factor;
+    int offset = (m_totalVerticalDeltas / 120) * factor;
     if (offset != 0) {
         if (isRightToLeft()) {
             m_scrollBar->animateToValue(m_scrollBar->value() + offset);
@@ -1740,7 +1745,7 @@ void TabBarScrollWidget::scrollByWheel(QWheelEvent* event)
             m_scrollBar->animateToValue(m_scrollBar->value() - offset);
         }
 
-        m_totalDeltas -= (offset / factor) * 120;
+        m_totalVerticalDeltas -= (offset / factor) * 120;
     }
 }
 
@@ -1809,7 +1814,11 @@ QSize CloseButton::sizeHint() const
     return QSize(width, height);
 }
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 void CloseButton::enterEvent(QEvent* event)
+#else
+void CloseButton::enterEvent(QEnterEvent* event)
+#endif
 {
     if (isEnabled()) {
         update();
@@ -1831,7 +1840,7 @@ void CloseButton::paintEvent(QPaintEvent*)
 {
     QPainter p(this);
     QStyleOption opt;
-    opt.init(this);
+    opt.initFrom(this);
     opt.state |= QStyle::State_AutoRaise;
 
     // update raised state on scrolling
diff --git a/src/lib/tabwidget/combotabbar.h b/src/lib/tabwidget/combotabbar.h
index c06dda6da..f40f24059 100644
--- a/src/lib/tabwidget/combotabbar.h
+++ b/src/lib/tabwidget/combotabbar.h
@@ -350,7 +350,7 @@ private:
     ToolButton* m_rightScrollButton;
     ToolButton* m_leftScrollButton;
     bool m_usesScrollButtons;
-    int m_totalDeltas;
+    int m_totalVerticalDeltas;
 };
 
 // Class for close button on tabs
@@ -364,7 +364,11 @@ public:
 
     QSize sizeHint() const override;
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     void enterEvent(QEvent *event) override;
+#else
+    void enterEvent(QEnterEvent *event) override;
+#endif
     void leaveEvent(QEvent *event) override;
     void paintEvent(QPaintEvent *event) override;
 };
diff --git a/src/lib/tabwidget/tabicon.cpp b/src/lib/tabwidget/tabicon.cpp
index da21d658c..7a361d253 100644
--- a/src/lib/tabwidget/tabicon.cpp
+++ b/src/lib/tabwidget/tabicon.cpp
@@ -24,6 +24,7 @@
 #include <QTimer>
 #include <QToolTip>
 #include <QMouseEvent>
+#include <QPainter>
 
 TabIcon::TabIcon(QWidget* parent)
     : QWidget(parent)
diff --git a/src/lib/tools/buttonwithmenu.cpp b/src/lib/tools/buttonwithmenu.cpp
index a854984b1..87db07d63 100644
--- a/src/lib/tools/buttonwithmenu.cpp
+++ b/src/lib/tools/buttonwithmenu.cpp
@@ -160,7 +160,11 @@ void ButtonWithMenu::generateMenu()
 
     for (const Item &item : qAsConst(m_items)) {
         QVariant variant;
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
         variant.setValue<Item>(item);
+#else
+        variant.setValue(item);
+#endif
         m_menu->addAction(item.icon, item.text, this, SLOT(setCurrentItem()))->setData(variant);
     }
 }
diff --git a/src/lib/tools/buttonwithmenu.h b/src/lib/tools/buttonwithmenu.h
index 5a50c1ffa..a68360f0a 100644
--- a/src/lib/tools/buttonwithmenu.h
+++ b/src/lib/tools/buttonwithmenu.h
@@ -38,7 +38,7 @@ public:
             icon = b;
         }
 
-        bool operator==(const Item &a) {
+        bool operator==(const Item &a) const {
             return (a.text == text) && (a.icon.pixmap(16).toImage() == icon.pixmap(16).toImage());
         }
 
diff --git a/src/lib/tools/desktopfile.cpp b/src/lib/tools/desktopfile.cpp
index 7394dadef..1155274fe 100644
--- a/src/lib/tools/desktopfile.cpp
+++ b/src/lib/tools/desktopfile.cpp
@@ -19,6 +19,7 @@
 
 #include <QSettings>
 #include <QStandardPaths>
+#include <QLocale>
 
 DesktopFile::DesktopFile()
 = default;
@@ -26,7 +27,9 @@ DesktopFile::DesktopFile()
 DesktopFile::DesktopFile(const QString &fileName)
 {
     m_settings.reset(new QSettings(fileName, QSettings::IniFormat));
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     m_settings->setIniCodec("UTF-8");
+#endif
     m_settings->beginGroup(QSL("Desktop Entry"));
 }
 
diff --git a/src/lib/tools/html5permissions/html5permissionsnotification.cpp b/src/lib/tools/html5permissions/html5permissionsnotification.cpp
index 106c2464e..1d56d8830 100644
--- a/src/lib/tools/html5permissions/html5permissionsnotification.cpp
+++ b/src/lib/tools/html5permissions/html5permissionsnotification.cpp
@@ -23,6 +23,7 @@
 
 #include <QTimer>
 #include <QWebEnginePage>
+#include <QWebEngineView>
 #include <QtWebEngineWidgetsVersion>
 
 
@@ -100,7 +101,11 @@ void HTML5PermissionsNotification::grantPermissions()
     QTimer::singleShot(0, this, [this]() {
         // We need to have cursor inside view to correctly grab mouse
         if (m_feature == QWebEnginePage::MouseLock) {
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
             QWidget *view = m_page->view();
+#else
+            QWidget *view = QWebEngineView::forPage(m_page);
+#endif
             QCursor::setPos(view->mapToGlobal(view->rect().center()));
         }
 
diff --git a/src/lib/tools/progressbar.cpp b/src/lib/tools/progressbar.cpp
index a51ba0870..b92622ef5 100644
--- a/src/lib/tools/progressbar.cpp
+++ b/src/lib/tools/progressbar.cpp
@@ -18,7 +18,7 @@
 #include "progressbar.h"
 
 #include <QStylePainter>
-#include <QStyleOptionProgressBarV2>
+#include <QStyleOptionProgressBar>
 
 ProgressBar::ProgressBar(QWidget* parent)
     : QWidget(parent)
diff --git a/src/lib/tools/qztools.cpp b/src/lib/tools/qztools.cpp
index 16214207c..9cfc41e3c 100644
--- a/src/lib/tools/qztools.cpp
+++ b/src/lib/tools/qztools.cpp
@@ -32,7 +32,11 @@
 #include <QWidget>
 #include <QApplication>
 #include <QSslCertificate>
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 #include <QDesktopWidget>
+#else
+#include <QScreen>
+#endif
 #include <QUrl>
 #include <QIcon>
 #include <QFileIconProvider>
@@ -115,7 +119,11 @@ QByteArray QzTools::readAllFileByteContents(const QString &filename)
 
 void QzTools::centerWidgetOnScreen(QWidget* w)
 {
-    const QRect screen = QApplication::desktop()->screenGeometry(w);
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
+    QRect screen = QApplication::desktop()->screenGeometry(w);
+#else
+    QRect screen = w->screen()->geometry();
+#endif
     const QRect size = w->geometry();
     w->move((screen.width() - size.width()) / 2, (screen.height() - size.height()) / 2);
 }
diff --git a/src/lib/webengine/webhittestresult.cpp b/src/lib/webengine/webhittestresult.cpp
index 88ddf4268..27c9caa22 100644
--- a/src/lib/webengine/webhittestresult.cpp
+++ b/src/lib/webengine/webhittestresult.cpp
@@ -18,7 +18,11 @@
 #include "webhittestresult.h"
 #include "webpage.h"
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 #include <QWebEngineContextMenuData>
+#else
+#include <QWebEngineContextMenuRequest>
+#endif
 
 WebHitTestResult::WebHitTestResult(const WebPage *page, const QPoint &pos)
     : m_isNull(true)
@@ -92,9 +96,14 @@ WebHitTestResult::WebHitTestResult(const WebPage *page, const QPoint &pos)
     init(p->url(), p->execJavaScript(js, WebPage::SafeJsWorld).toMap());
 }
 
-void WebHitTestResult::updateWithContextMenuData(const QWebEngineContextMenuData &data)
+void WebHitTestResult::updateWithContextMenuData(const Q_WEB_ENGINE_CONTEXT_MENU_DATA_CLASS &data)
 {
-    if (!data.isValid() || data.position() != m_pos) {
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
+    if (!data.isValid()) {
+        return;
+    }
+#endif
+    if (data.position() != m_pos) {
         return;
     }
 
@@ -104,12 +113,12 @@ void WebHitTestResult::updateWithContextMenuData(const QWebEngineContextMenuData
     m_isContentSelected = !data.selectedText().isEmpty();
 
     switch (data.mediaType()) {
-    case QWebEngineContextMenuData::MediaTypeImage:
+    case Q_WEB_ENGINE_CONTEXT_MENU_DATA_CLASS::MediaTypeImage:
         m_imageUrl = data.mediaUrl();
         break;
 
-    case QWebEngineContextMenuData::MediaTypeVideo:
-    case QWebEngineContextMenuData::MediaTypeAudio:
+    case Q_WEB_ENGINE_CONTEXT_MENU_DATA_CLASS::MediaTypeVideo:
+    case Q_WEB_ENGINE_CONTEXT_MENU_DATA_CLASS::MediaTypeAudio:
         m_mediaUrl = data.mediaUrl();
         break;
 
diff --git a/src/lib/webengine/webhittestresult.h b/src/lib/webengine/webhittestresult.h
index 98f7174d7..7b939472a 100644
--- a/src/lib/webengine/webhittestresult.h
+++ b/src/lib/webengine/webhittestresult.h
@@ -25,7 +25,13 @@
 
 #include "qzcommon.h"
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 class QWebEngineContextMenuData;
+#define Q_WEB_ENGINE_CONTEXT_MENU_DATA_CLASS QWebEngineContextMenuData
+#else
+class QWebEngineContextMenuRequest;
+#define Q_WEB_ENGINE_CONTEXT_MENU_DATA_CLASS QWebEngineContextMenuRequest
+#endif
 
 class WebPage;
 
@@ -34,7 +40,7 @@ class FALKON_EXPORT WebHitTestResult
 public:
     explicit WebHitTestResult(const WebPage *page, const QPoint &pos);
 
-    void updateWithContextMenuData(const QWebEngineContextMenuData &data);
+    void updateWithContextMenuData(const Q_WEB_ENGINE_CONTEXT_MENU_DATA_CLASS &data);
 
     QUrl baseUrl() const;
     QString alternateText() const;
diff --git a/src/lib/webengine/webpage.cpp b/src/lib/webengine/webpage.cpp
index 15f91e53b..d4e553d8a 100644
--- a/src/lib/webengine/webpage.cpp
+++ b/src/lib/webengine/webpage.cpp
@@ -89,6 +89,9 @@ WebPage::WebPage(QObject* parent)
     connect(this, &QWebEnginePage::windowCloseRequested, this, &WebPage::windowCloseRequested);
     connect(this, &QWebEnginePage::fullScreenRequested, this, &WebPage::fullScreenRequested);
     connect(this, &QWebEnginePage::renderProcessTerminated, this, &WebPage::renderProcessTerminated);
+#if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
+    connect(this, &QWebEnginePage::certificateError, this, &WebPage::onCertificateError);
+#endif
 
     connect(this, &QWebEnginePage::authenticationRequired, this, [this](const QUrl &url, QAuthenticator *auth) {
         mApp->networkManager()->authentication(url, auth, view());
@@ -137,7 +140,11 @@ WebPage::~WebPage()
 
 WebView *WebPage::view() const
 {
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     return static_cast<WebView*>(QWebEnginePage::view());
+#else
+    return static_cast<WebView*>(QWebEngineView::forPage(this));
+#endif
 }
 
 bool WebPage::execPrintPage(QPrinter *printer, int timeout)
@@ -146,12 +153,22 @@ bool WebPage::execPrintPage(QPrinter *printer, int timeout)
     bool result = false;
     QTimer::singleShot(timeout, loop.data(), &QEventLoop::quit);
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     print(printer, [loop, &result](bool res) {
         if (loop && loop->isRunning()) {
             result = res;
             loop->quit();
         }
     });
+#else
+    connect(view(), &QWebEngineView::printFinished, this, [loop, &result](bool res) {
+        if (loop && loop->isRunning()) {
+            result = res;
+            loop->quit();
+        }
+    });
+    view()->print(printer);
+#endif
 
     loop->exec();
     delete loop;
@@ -463,10 +480,21 @@ bool WebPage::acceptNavigationRequest(const QUrl &url, QWebEnginePage::Navigatio
     return result;
 }
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 bool WebPage::certificateError(const QWebEngineCertificateError &error)
 {
     return mApp->networkManager()->certificateError(error, view());
 }
+#else
+void WebPage::onCertificateError(QWebEngineCertificateError error)
+{
+    auto mutableError = const_cast<QWebEngineCertificateError&>(error);
+    if (mApp->networkManager()->certificateError(mutableError, view()))
+        mutableError.acceptCertificate();
+    else
+        mutableError.rejectCertificate();
+}
+#endif
 
 QStringList WebPage::chooseFiles(QWebEnginePage::FileSelectionMode mode, const QStringList &oldFiles, const QStringList &acceptedMimeTypes)
 {
diff --git a/src/lib/webengine/webpage.h b/src/lib/webengine/webpage.h
index a61e8c41d..425bb3bc2 100644
--- a/src/lib/webengine/webpage.h
+++ b/src/lib/webengine/webpage.h
@@ -21,6 +21,9 @@
 #include <QWebEnginePage>
 #include <QWebEngineScript>
 #include <QWebEngineFullScreenRequest>
+#if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
+#include <QPrinter>
+#endif
 #include <QVector>
 #include <QElapsedTimer>
 
@@ -93,10 +96,15 @@ private Q_SLOTS:
     void fullScreenRequested(QWebEngineFullScreenRequest fullScreenRequest);
     void featurePermissionRequested(const QUrl &origin, const QWebEnginePage::Feature &feature);
     void renderProcessTerminated(QWebEnginePage::RenderProcessTerminationStatus terminationStatus, int exitCode);
+#if (QT_VERSION >= QT_VERSION_CHECK(6, 0, 0))
+    void onCertificateError(QWebEngineCertificateError error);
+#endif
 
 private:
     bool acceptNavigationRequest(const QUrl &url, QWebEnginePage::NavigationType type, bool isMainFrame) override;
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     bool certificateError(const QWebEngineCertificateError &error) override;
+#endif
     QStringList chooseFiles(FileSelectionMode mode, const QStringList &oldFiles, const QStringList &acceptedMimeTypes) override;
     QWebEnginePage* createWindow(QWebEnginePage::WebWindowType type) override;
 
diff --git a/src/lib/webengine/webscrollbar.cpp b/src/lib/webengine/webscrollbar.cpp
index e294dbbf0..24e0e4f9c 100644
--- a/src/lib/webengine/webscrollbar.cpp
+++ b/src/lib/webengine/webscrollbar.cpp
@@ -21,6 +21,7 @@
 #include "webpage.h"
 
 #include <QPaintEvent>
+#include <QPainter>
 
 WebScrollBar::WebScrollBar(Qt::Orientation orientation, WebView *view)
     : QScrollBar(orientation)
diff --git a/src/lib/webengine/webscrollbarmanager.cpp b/src/lib/webengine/webscrollbarmanager.cpp
index 96f2cda29..7a0e3fd7e 100644
--- a/src/lib/webengine/webscrollbarmanager.cpp
+++ b/src/lib/webengine/webscrollbarmanager.cpp
@@ -26,6 +26,7 @@
 
 #include <QPointer>
 #include <QPaintEvent>
+#include <QPainter>
 #include <QWebEngineProfile>
 #include <QWebEngineScriptCollection>
 #include <QStyle>
@@ -210,8 +211,14 @@ void WebScrollBarManager::createUserScript(int thickness)
 
 void WebScrollBarManager::removeUserScript()
 {
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     QWebEngineScript script = mApp->webProfile()->scripts()->findScript(QSL("_falkon_scrollbar"));
     mApp->webProfile()->scripts()->remove(script);
+#else
+    for (const QWebEngineScript &script : mApp->webProfile()->scripts()->find(QSL("_falkon_scrollbar"))) {
+        mApp->webProfile()->scripts()->remove(script);
+    }
+#endif
 }
 
 QSize WebScrollBarManager::viewportSize(WebView *view, int thickness) const
diff --git a/src/lib/webengine/webview.cpp b/src/lib/webengine/webview.cpp
index 0d68da7bb..54dd7826d 100644
--- a/src/lib/webengine/webview.cpp
+++ b/src/lib/webengine/webview.cpp
@@ -44,7 +44,11 @@
 #include <QWebEngineHistory>
 #include <QClipboard>
 #include <QMimeData>
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 #include <QWebEngineContextMenuData>
+#else
+#include <QWebEngineContextMenuRequest>
+#endif
 #include <QStackedLayout>
 #include <QScrollBar>
 #include <QPrintDialog>
@@ -146,7 +150,9 @@ void WebView::setPage(WebPage *page)
             Q_EMIT m_page->loadFinished(true);
         }
         mApp->plugins()->emitWebPageDeleted(m_page);
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
         m_page->setView(nullptr);
+#endif
     }
 
     page->setParent(this);
@@ -403,10 +409,17 @@ void WebView::printPage()
             m_page->printToPdf(dialog->printer()->outputFileName(), dialog->printer()->pageLayout());
             delete dialog;
         } else {
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
             m_page->print(dialog->printer(), [=](bool success) {
                 Q_UNUSED(success);
                 delete dialog;
             });
+#else
+            connect(this, &QWebEngineView::printFinished, this, [&dialog](bool success) {
+                Q_UNUSED(success);
+                delete dialog;
+            });
+#endif
         }
     }
 }
@@ -670,7 +683,15 @@ void WebView::createContextMenu(QMenu *menu, WebHitTestResult &hitTest)
     // cppcheck-suppress variableScope
     int spellCheckActionCount = 0;
 
-    const QWebEngineContextMenuData &contextMenuData = page()->contextMenuData();
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
+    const Q_WEB_ENGINE_CONTEXT_MENU_DATA_CLASS &contextMenuData = page()->contextMenuData();
+#else
+    const Q_WEB_ENGINE_CONTEXT_MENU_DATA_CLASS *contextMenuDataPtr = lastContextMenuRequest();
+    if (contextMenuDataPtr == NULL)
+        return;
+    const Q_WEB_ENGINE_CONTEXT_MENU_DATA_CLASS &contextMenuData = *contextMenuDataPtr;
+#endif
+
     hitTest.updateWithContextMenuData(contextMenuData);
 
     if (!contextMenuData.misspelledWord().isEmpty()) {
diff --git a/src/lib/webtab/searchtoolbar.cpp b/src/lib/webtab/searchtoolbar.cpp
index 8bdf59825..906671558 100644
--- a/src/lib/webtab/searchtoolbar.cpp
+++ b/src/lib/webtab/searchtoolbar.cpp
@@ -121,7 +121,12 @@ void SearchToolBar::searchText(const QString &text)
 {
     m_searchRequests++;
     QPointer<SearchToolBar> guard = this;
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     m_view->findText(text, m_findFlags, [=](bool found) {
+#else
+    m_view->findText(text, m_findFlags, [=](QWebEngineFindTextResult result) {
+        bool found = result.numberOfMatches() > 0;
+#endif
         if (!guard) {
             return;
         }
diff --git a/src/lib/webtab/searchtoolbar.h b/src/lib/webtab/searchtoolbar.h
index af07087e5..00fdc5cb9 100644
--- a/src/lib/webtab/searchtoolbar.h
+++ b/src/lib/webtab/searchtoolbar.h
@@ -18,6 +18,7 @@
 #ifndef SEARCHTOOLBAR_H
 #define SEARCHTOOLBAR_H
 
+#include <QWidget>
 #include <QWebEnginePage>
 #include <QtWebEngineCoreVersion>
 
diff --git a/src/main/CMakeLists.txt b/src/main/CMakeLists.txt
index 835d48d11..2ec3f7006 100644
--- a/src/main/CMakeLists.txt
+++ b/src/main/CMakeLists.txt
@@ -32,10 +32,11 @@ endif()
 if (UNIX AND NOT APPLE)
     install(TARGETS falkon ${KDE_INSTALL_TARGETS_DEFAULT_ARGS})
     install(DIRECTORY ${CMAKE_SOURCE_DIR}/themes DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/falkon)
-    if (KF5I18n_FOUND)
+    if (KF${KF_MAJOR_VERSION}I18n_FOUND)
         ki18n_install(${CMAKE_SOURCE_DIR}/po)
     endif()
-    ecm_install_po_files_as_qm(${CMAKE_SOURCE_DIR}/poqm)
+    # TODO Qt6 port ?
+    #ecm_install_po_files_as_qm(${CMAKE_SOURCE_DIR}/poqm)
 
     install(PROGRAMS ../../linux/applications/org.kde.falkon.desktop DESTINATION ${KDE_INSTALL_APPDIR})
 
diff --git a/src/plugins/AutoScroll/autoscroller.cpp b/src/plugins/AutoScroll/autoscroller.cpp
index 55cb41536..341eee881 100644
--- a/src/plugins/AutoScroll/autoscroller.cpp
+++ b/src/plugins/AutoScroll/autoscroller.cpp
@@ -25,6 +25,7 @@
 #include <QMouseEvent>
 #include <QSettings>
 #include <QIcon>
+#include <QPainter>
 
 ScrollIndicator::ScrollIndicator(QWidget *parent)
     : QLabel(parent)
diff --git a/src/plugins/CMakeLists.txt b/src/plugins/CMakeLists.txt
index 54b28ba98..48702bfd0 100644
--- a/src/plugins/CMakeLists.txt
+++ b/src/plugins/CMakeLists.txt
@@ -6,8 +6,8 @@ add_subdirectory(GreaseMonkey)
 add_subdirectory(MouseGestures)
 add_subdirectory(PIM)
 add_subdirectory(StatusBarIcons)
-add_subdirectory(TabManager)
-add_subdirectory(VerticalTabs)
+## TODO ## add_subdirectory(TabManager)
+## TODO ## add_subdirectory(VerticalTabs)
 
 if (GNOME_KEYRING_FOUND)
     add_subdirectory(GnomeKeyringPasswords)
diff --git a/src/plugins/FlashCookieManager/fcm_plugin.h b/src/plugins/FlashCookieManager/fcm_plugin.h
index 056bcb024..684c278b0 100644
--- a/src/plugins/FlashCookieManager/fcm_plugin.h
+++ b/src/plugins/FlashCookieManager/fcm_plugin.h
@@ -37,7 +37,7 @@ struct FlashCookie {
     QString contents;
     QDateTime lastModification;
 
-    bool operator ==(const FlashCookie &other) {
+    bool operator ==(const FlashCookie &other) const {
         return (this->name == other.name && this->path == other.path);
     }
 };
diff --git a/src/plugins/GreaseMonkey/gm_manager.cpp b/src/plugins/GreaseMonkey/gm_manager.cpp
index 4c7ade256..be1e9c09e 100644
--- a/src/plugins/GreaseMonkey/gm_manager.cpp
+++ b/src/plugins/GreaseMonkey/gm_manager.cpp
@@ -182,7 +182,13 @@ void GM_Manager::disableScript(GM_Script* script)
     m_disabledScripts.append(script->fullName());
 
     QWebEngineScriptCollection *collection = mApp->webProfile()->scripts();
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     collection->remove(collection->findScript(script->fullName()));
+#else
+    for (const auto &script : collection->find(script->fullName())) {
+        collection->remove(script);
+    }
+#endif
 }
 
 bool GM_Manager::addScript(GM_Script* script)
@@ -210,7 +216,13 @@ bool GM_Manager::removeScript(GM_Script* script, bool removeFile)
     m_scripts.removeOne(script);
 
     QWebEngineScriptCollection *collection = mApp->webProfile()->scripts();
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     collection->remove(collection->findScript(script->fullName()));
+#else
+    for (const auto &script : collection->find(script->fullName())) {
+        collection->remove(script);
+    }
+#endif
 
     m_disabledScripts.removeOne(script->fullName());
 
@@ -279,7 +291,13 @@ void GM_Manager::scriptChanged()
         return;
 
     QWebEngineScriptCollection *collection = mApp->webProfile()->scripts();
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     collection->remove(collection->findScript(script->fullName()));
+#else
+    for (const auto &script : collection->find(script->fullName())) {
+        collection->remove(script);
+    }
+#endif
     collection->insert(script->webScript());
 }
 
diff --git a/src/plugins/GreaseMonkey/settings/gm_settingslistdelegate.cpp b/src/plugins/GreaseMonkey/settings/gm_settingslistdelegate.cpp
index c60a33d04..356d40c62 100644
--- a/src/plugins/GreaseMonkey/settings/gm_settingslistdelegate.cpp
+++ b/src/plugins/GreaseMonkey/settings/gm_settingslistdelegate.cpp
@@ -90,9 +90,9 @@ void GM_SettingsListDelegate::paint(QPainter* painter, const QStyleOptionViewIte
     const int checkboxYPos = center - (checkboxSize / 2);
     QStyleOptionViewItem opt2 = opt;
     opt2.checkState == Qt::Checked ? opt2.state |= QStyle::State_On : opt2.state |= QStyle::State_Off;
-    QRect styleCheckBoxRect = style->subElementRect(QStyle::SE_ViewItemCheckIndicator, &opt2, w);
+    QRect styleCheckBoxRect = style->subElementRect(QStyle::SE_ItemViewItemCheckIndicator, &opt2, w);
     opt2.rect = QRect(leftPosition, checkboxYPos, styleCheckBoxRect.width(), styleCheckBoxRect.height());
-    style->drawPrimitive(QStyle::PE_IndicatorViewItemCheck, &opt2, painter, w);
+    style->drawPrimitive(QStyle::PE_IndicatorItemViewItemCheck, &opt2, painter, w);
     leftPosition = opt2.rect.right() + m_padding;
 
     // Draw icon
diff --git a/src/plugins/PyFalkon/CMakeLists.txt b/src/plugins/PyFalkon/CMakeLists.txt
index 13890db61..b0edcd924 100644
--- a/src/plugins/PyFalkon/CMakeLists.txt
+++ b/src/plugins/PyFalkon/CMakeLists.txt
@@ -4,13 +4,13 @@ if(POLICY CMP0071)
 endif()
 
 # Get all relevant Qt include dirs, to pass them on to shiboken.
-get_property(QT_CORE_INCLUDE_DIRS TARGET Qt5::Core PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
-get_property(QT_GUI_INCLUDE_DIRS TARGET Qt5::Gui PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
-get_property(QT_SQL_INCLUDE_DIRS TARGET Qt5::Sql PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
-get_property(QT_WIDGETS_INCLUDE_DIRS TARGET Qt5::Widgets PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
-get_property(QT_NETWORK_INCLUDE_DIRS TARGET Qt5::Network PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
-get_property(QT_WEBENGINECORE_INCLUDE_DIRS TARGET Qt5::WebEngineCore PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
-get_property(QT_WEBENGINEWIDGETS_INCLUDE_DIRS TARGET Qt5::WebEngineWidgets PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
+get_property(QT_CORE_INCLUDE_DIRS TARGET Qt${QT_MAJOR_VERSION}::Core PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
+get_property(QT_GUI_INCLUDE_DIRS TARGET Qt${QT_MAJOR_VERSION}::Gui PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
+get_property(QT_SQL_INCLUDE_DIRS TARGET Qt${QT_MAJOR_VERSION}::Sql PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
+get_property(QT_WIDGETS_INCLUDE_DIRS TARGET Qt${QT_MAJOR_VERSION}::Widgets PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
+get_property(QT_NETWORK_INCLUDE_DIRS TARGET Qt${QT_MAJOR_VERSION}::Network PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
+get_property(QT_WEBENGINECORE_INCLUDE_DIRS TARGET Qt${QT_MAJOR_VERSION}::WebEngineCore PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
+get_property(QT_WEBENGINEWIDGETS_INCLUDE_DIRS TARGET Qt${QT_MAJOR_VERSION}::WebEngineWidgets PROPERTY INTERFACE_INCLUDE_DIRECTORIES)
 set(QT_INCLUDE_DIRS
     ${QT_CORE_INCLUDE_DIRS}
     ${QT_GUI_INCLUDE_DIRS}
@@ -134,9 +134,15 @@ set(GENERATED_SOURCES_DEPENDENCIES
     ${TYPESYSTEM_FILE}
 )
 
+if (QT_MAJOR_VERSION STREQUAL "6")
+    set(PYSIDE_VERSION "6")
+else()
+    set(PYSIDE_VERSION "2")
+endif()
+
 # Add custom target to run shiboken.
 add_custom_command(OUTPUT ${GENERATED_SOURCES}
-                    COMMAND Shiboken2::shiboken2
+                    COMMAND Shiboken${PYSIDE_VERSION}::shiboken${PYSIDE_VERSION}
                     ${SHIBOKEN_OPTIONS} ${GLOBAL_HEADER} ${TYPESYSTEM_FILE}
                     DEPENDS ${GENERATED_SOURCES_DEPENDENCIES}
                     WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
@@ -144,7 +150,7 @@ add_custom_command(OUTPUT ${GENERATED_SOURCES}
 
 # We need to include the headers for the module bindings that we use.
 set(PYSIDE_ADDITIONAL_INCLUDES "")
-get_target_property(PYSIDE_INCLUDE_DIRS PySide2::pyside2 INTERFACE_INCLUDE_DIRECTORIES)
+get_target_property(PYSIDE_INCLUDE_DIRS PySide${PYSIDE_VERSION}::pyside${PYSIDE_VERSION} INTERFACE_INCLUDE_DIRECTORIES)
 foreach(INCLUDE_DIR ${PYSIDE_INCLUDE_DIRS})
     list(APPEND PYSIDE_ADDITIONAL_INCLUDES "${INCLUDE_DIR}/QtCore")
     list(APPEND PYSIDE_ADDITIONAL_INCLUDES "${INCLUDE_DIR}/QtGui")
@@ -175,8 +181,8 @@ target_include_directories(PyFalkon
 target_link_libraries(PyFalkon
     PRIVATE
     FalkonPrivate
-    Shiboken2::libshiboken
-    PySide2::pyside2
+    Shiboken${PYSIDE_VERSION}::libshiboken
+    PySide${PYSIDE_VERSION}::pyside${PYSIDE_VERSION}
     Python3::Python
 )
 
diff --git a/src/plugins/PyFalkon/autotests/CMakeLists.txt b/src/plugins/PyFalkon/autotests/CMakeLists.txt
index b629debc2..cee804585 100644
--- a/src/plugins/PyFalkon/autotests/CMakeLists.txt
+++ b/src/plugins/PyFalkon/autotests/CMakeLists.txt
@@ -6,7 +6,7 @@ macro(pyfalkon_tests)
 endmacro()
 
 add_executable(pyfalkontestrunner pyfalkontestrunner.cpp)
-target_link_libraries(pyfalkontestrunner FalkonPrivate Qt5::Test)
+target_link_libraries(pyfalkontestrunner FalkonPrivate Qt${QT_MAJOR_VERSION}::Test)
 
 pyfalkon_tests(
     basictest
diff --git a/src/plugins/StatusBarIcons/sbi_networkicon.cpp b/src/plugins/StatusBarIcons/sbi_networkicon.cpp
index 1c85ce61d..f8fbd0ce7 100644
--- a/src/plugins/StatusBarIcons/sbi_networkicon.cpp
+++ b/src/plugins/StatusBarIcons/sbi_networkicon.cpp
@@ -23,18 +23,26 @@
 #include "browserwindow.h"
 
 #include <QMenu>
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 #include <QNetworkConfigurationManager>
+#endif
 
 SBI_NetworkIcon::SBI_NetworkIcon(BrowserWindow* window)
     : SBI_Icon(window)
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     , m_networkConfiguration(new QNetworkConfigurationManager(this))
+#endif
 {
     setObjectName(QSL("sbi_networkicon"));
     setCursor(Qt::PointingHandCursor);
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     onlineStateChanged(m_networkConfiguration->isOnline());
 
     connect(m_networkConfiguration, &QNetworkConfigurationManager::onlineStateChanged, this, &SBI_NetworkIcon::onlineStateChanged);
+#else
+    onlineStateChanged(true);
+#endif
     connect(this, &ClickableLabel::clicked, this, &SBI_NetworkIcon::showMenu);
 }
 
@@ -97,12 +105,16 @@ void SBI_NetworkIcon::updateToolTip()
 {
     QString tooltip = tr("Shows network status and manages proxy<br/><br/><b>Network:</b><br/>%1<br/><br/><b>Proxy:</b><br/>%2");
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     if (m_networkConfiguration->isOnline()) {
         tooltip = tooltip.arg(tr("Connected"));
     }
     else {
         tooltip = tooltip.arg(tr("Offline"));
     }
+#else
+    tooltip = tooltip.arg(tr("Connected"));
+#endif
 
     switch (QNetworkProxy::applicationProxy().type()) {
     case QNetworkProxy::DefaultProxy:
@@ -125,7 +137,11 @@ void SBI_NetworkIcon::updateToolTip()
     setToolTip(tooltip);
 }
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 void SBI_NetworkIcon::enterEvent(QEvent* event)
+#else
+void SBI_NetworkIcon::enterEvent(QEnterEvent* event)
+#endif
 {
     updateToolTip();
 
diff --git a/src/plugins/StatusBarIcons/sbi_networkicon.h b/src/plugins/StatusBarIcons/sbi_networkicon.h
index cbe9d8c05..c59b1a2d9 100644
--- a/src/plugins/StatusBarIcons/sbi_networkicon.h
+++ b/src/plugins/StatusBarIcons/sbi_networkicon.h
@@ -40,9 +40,16 @@ private Q_SLOTS:
 
 private:
     void updateToolTip();
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     void enterEvent(QEvent* event) override;
+#else
+    void enterEvent(QEnterEvent* event) override;
+#endif
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
+    // TODO - should we try to replace the online status detection using Qt 6?
     QNetworkConfigurationManager* m_networkConfiguration;
+#endif
 };
 
 #endif // SBI_NETWORKICON_H
diff --git a/src/plugins/TabManager/tabmanagerwidget.cpp b/src/plugins/TabManager/tabmanagerwidget.cpp
index 18b10423e..e67694449 100644
--- a/src/plugins/TabManager/tabmanagerwidget.cpp
+++ b/src/plugins/TabManager/tabmanagerwidget.cpp
@@ -34,7 +34,9 @@
 #include "tabcontextmenu.h"
 #include "tabbar.h"
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 #include <QDesktopWidget>
+#endif
 #include <QDialogButtonBox>
 #include <QStackedWidget>
 #include <QDialog>
@@ -561,7 +563,12 @@ void TabManagerWidget::detachSelectedTabs(const QMultiHash<BrowserWindow*, WebTa
     }
 
     BrowserWindow* newWindow = mApp->createWindow(Qz::BW_OtherRestoredWindow);
-    newWindow->move(mApp->desktop()->availableGeometry(this).topLeft() + QPoint(30, 30));
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
+    const QRect &availableGeometryForScreen = mApp->desktop()->availableGeometry(this);
+#else
+    const QRect &availableGeometryForScreen = screen()->availableGeometry();
+#endif
+    newWindow->move(availableGeometryForScreen.topLeft() + QPoint(30, 30));
 
     detachTabsTo(newWindow, tabsHash);
 }
@@ -880,7 +887,11 @@ QStringList TabTreeWidget::mimeTypes() const
     return types;
 }
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 QMimeData *TabTreeWidget::mimeData(const QList<QTreeWidgetItem*> items) const
+#else
+QMimeData *TabTreeWidget::mimeData(const QList<QTreeWidgetItem*> &items) const
+#endif
 {
     auto* mimeData = new QMimeData();
     QByteArray encodedData;
diff --git a/src/plugins/TabManager/tabmanagerwidget.h b/src/plugins/TabManager/tabmanagerwidget.h
index 9ded6857f..cb6ddc6f9 100644
--- a/src/plugins/TabManager/tabmanagerwidget.h
+++ b/src/plugins/TabManager/tabmanagerwidget.h
@@ -44,7 +44,11 @@ public:
 
     Qt::DropActions supportedDropActions() const override;
     QStringList mimeTypes() const override;
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     QMimeData* mimeData(const QList<QTreeWidgetItem*> items) const override;
+#else
+    QMimeData* mimeData(const QList<QTreeWidgetItem*> &items) const override;
+#endif
     bool dropMimeData(QTreeWidgetItem *parent, int index, const QMimeData *data, Qt::DropAction action) override;
 
     void setEnableDragTabs(bool enable);
diff --git a/src/plugins/TabManager/tabmanagerwidgetcontroller.cpp b/src/plugins/TabManager/tabmanagerwidgetcontroller.cpp
index 9de8d5a23..475d1dddf 100644
--- a/src/plugins/TabManager/tabmanagerwidgetcontroller.cpp
+++ b/src/plugins/TabManager/tabmanagerwidgetcontroller.cpp
@@ -25,7 +25,9 @@
 #include "statusbar.h"
 #include "navigationbar.h"
 
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
 #include <QDesktopWidget>
+#endif
 #include <QAction>
 #include <QStyle>
 
@@ -212,7 +214,12 @@ void TabManagerWidgetController::showSideBySide()
     if (!defaultTabManager()) {
         return;
     }
+
+#if (QT_VERSION < QT_VERSION_CHECK(6, 0, 0))
     const QRect &availableGeometry = mApp->desktop()->availableGeometry(defaultTabManager());
+#else
+    const QRect &availableGeometry = defaultTabManager()->screen()->availableGeometry();
+#endif
     static int frameWidth = (defaultTabManager()->frameGeometry().width() - defaultTabManager()->geometry().width()) / 2;
     static int titleBarHeight = defaultTabManager()->style()->pixelMetric(QStyle::PM_TitleBarHeight);
 
diff --git a/src/plugins/VerticalTabs/tabtreedelegate.cpp b/src/plugins/VerticalTabs/tabtreedelegate.cpp
index 8f078adb9..d67f8921c 100644
--- a/src/plugins/VerticalTabs/tabtreedelegate.cpp
+++ b/src/plugins/VerticalTabs/tabtreedelegate.cpp
@@ -213,7 +213,7 @@ void TabTreeDelegate::paint(QPainter *painter, const QStyleOptionViewItem &optio
     // Draw close button
     if (m_closeButton->isVisible(hovered, selected)) {
         QStyleOptionButton o;
-        o.init(m_closeButton);
+        o.initFrom(m_closeButton);
 
         const bool hovered = closeButtonRect(index).contains(m_view->viewport()->mapFromGlobal(QCursor::pos()));
         const bool pressed = hovered && QApplication::mouseButtons() == Qt::LeftButton;