Continued in #7202, most of the information below is purely historical.

The next Qt release after 5.15 will be Qt 6. The initial schedule plans for a release 2020-12-01, with feature freeze on 2020-08-31.

QtWebEngine is coming back with Qt 6.2. Release schedule:

• Feature freeze 2021-06-07
• Alpha 2021-06-23
• Beta 1 2021-07-6
• Beta 2 2021-07-27
• Beta 3 2021-08-17
• Beta 4 2021-08-31
• RC 2021-09-14
• Final 2021-09-30

Links:

• Interesting JIRA issues
• Interesting codereview changes: dev, 6.2

API changes

Probably going to be a bunch, but rather small changes... The plan for qutebrowser is to stay compatible with Qt 5 for a while, while gaining compatibility with Qt 6.

• Rename QWebEngineDownloadItem -> QWebEngineDownloadRequest
• Remove obsolete, deprecated api from qwebenginedownloaditem
• Unify certificate error handling
• Move QMenu handling from page to view
• Merge all webenginecontextmenudata wrappers into one class
• Improve QWebEngineCertificateError api
• Remove default qwebenginesettings getter
• Move qwebenginesettings to core
• Move QWebEngineFullScreenRequest to core
• Move to qwebenginescript to core
• Move qtwebenginescriptcollection class to core
• Cleanup qwebenginescript and qwebenginescriptcollection api
• Drop dependency on default notification presenter in profile
• Drop dependency on page in profile (internal only?)
• Move profile from widgets to core
• Remove deprecated url interoceptor setter from profile
• Move client certificate selection to core
• Remove qwebengineview setter from qwebenginepage
• Move QWebEngineHistory to core
• Move QWebEnginePage to core
• Add Qt WebEngine version getter
• Make handling of certificate errors possible from a signal
• Add missing FileSelectionMode enum value
• Move createWindow to a signal (internal only?)
• Move QQuickWebEngineNavigationRequest to Core
• Merge WebEngineHistory's quick implementation into QWebEngineHistory
• QWebEnginePage: add new 'loading' property and expose QWebEngineLoadingInfo
• Move printing finished callback to signal
• Add API for favicon database
• Remove left-over deprecated API QWebEngineProfile::setRequestInterceptor()
• Add QPageRanges to PDF printing
• Make default profile off the record
• Remove deprecated useforglobalcertificateverification

API review follow ups

• Remove duplicated 'downloadProgress' in favor of separate signals (Ib825d63c) · Gerrit Code Review
• Update parameters to findText callback (I622ff55c) · Gerrit Code Review
• Add QWebEngineNewWindowRequest::openIn(QWebEnginePage *) (I15e72d52) · Gerrit Code Review
• Add QWebEnginePage::view() replacement (I552f0047) · Gerrit Code Review
• Return printToPdf to QWebEnginePage (I0e14563c) · Gerrit Code Review

Interesting non-API changes

• Fix inconsistent number of load signals and their order (not an API change, but relevant for us)
• Implement dialogs of File System Access API (no API change, just potentially interesting)
• Add basic USB device logging (same)
• Suppress error pages also for http errors if they are disabled (no API change, but interesting)
• Disable kAllowContentInitiatedDataUrlNavigations (I9398f54b) · Gerrit Code Review
• Widgets (like the command text box) now insert test into the primary selection (if available) (ignore the fix version, it only made it into 6.0 but didn't get a new ticket)

Planned changes in PyQt

• PyQt5 -> PyQt6 rename (see Add wrapper modules for PyQt #995)
• Enums won't be accessible unscoped, only scoped - scoped access is possible since Qt 5.11 I believe, so if we want to access enum members without some unwieldy enum_value(QWebEnginePage, 'FindFlag', 'FindBackward') wrapper, we'll need to drop older versions at that point (Dropping support for Qt < 5.12 (affects Debian Stretch/Buster, Ubuntu 18.04) #3839) - split off to Rewrite enum access for scoped PyQt enums #5904.

More from the website:

PyQt6 introduces the following incompatibilities over PyQt5:

• The Qt module has been removed.
• QtWidgets.qApp has been removed.
• The QtCore.PYQT_CONFIGURATION dict has been removed.
• pyrcc has been removed.
• Scoped enums are now implemented as enum.Enum (PyQt5 used enum.IntEnum). Named enums are now implemented as enum.IntEnum (PyQt5 used a custom type). PyQt5 allowed an int whenever an enum was expected. PyQt6 requires the correct type (ie. it will not accept an int instead of an enum).
• All exec_() methods have been removed.
• All print_() methods have been removed.
• Python v3.6 or later is required.

Changes which probably didn't make it

• Add QWebEngineurlRequestBody (Ia0e4b5a5) · Gerrit Code Review
• Add a new signal "launchExternalProtocol" when launching external url (I744b6ca9) · Gerrit Code Review
• Clear the cache in time range (If80bba20) · Gerrit Code Review
• Add QWebEngineurlRequestBody (Ia0e4b5a5) · Gerrit Code Review
• Add QWebEnginePage::httpStatusCode() (I350c003e) · Gerrit Code Review