Problem: cannot install the best update candidate for package kf5-kwayland-5.110.0-1.fc39.x86_64
  - nothing provides kf5-filesystem >= 5.111.0 needed by kf5-kwayland-5.111.0-2.fc39.x86_64 from advisory

I guess it's missing a kf5-filesystem build?

Problems with kf5-kwayland-5.111.0-2.fc39 and kf5-akonadi-server-23.08.2-2.fc39 and the Qt 5.15.11 update were shown that prevent them from being updated https://bugzilla.redhat.com/show_bug.cgi?id=2244760 F39 has kf5 5.110.0 and KDE Gear 23.08.1, but kf5-kwayland-5.111.0-2.fc39, kf5-frameworkintegration-5.111.0-2.fc39 and kf5-akonadi-server-23.08.2-2.fc39 were in the update. This problem might be fixed by rebuilding kf5-kwayland-5.110.0, kf5-frameworkintegration-5.110.0 and kf5-akonadi-server-23.08.1 and adding them to the update. Otherwise, building the rest of KF5 5.111.0 in F39 and adding it to the update might fix this. Problems with qadwaitadecorations-0.1.2-5.fc39 and the Qt 5.15.11 and Qt 6.6.0 updates were also shown https://bugzilla.redhat.com/show_bug.cgi?id=2244757

telegram-desktop segfaults after QT6 update

https://lists.opensuse.org/archives/list/factory@lists.opensuse.org/thread/M53D4PDB2Q5FIJA6XU4KPLJBPM362VUT/

This is a regression introduced with qt6-svg; the original Qt bug report is here:

https://bugreports.qt.io/browse/QTBUG-117944

Looks like a few other packages need to be rebuilt with the QT5/6 update

Problem 1: problem with installed package calibre-6.21.0-5.fc39.x86_64
  - package calibre-6.21.0-5.fc39.x86_64 from @System requires libQt6Gui.so.6(Qt_6.5_PRIVATE_API)(64bit), but none of the providers can be installed
  - package calibre-6.21.0-5.fc39.x86_64 from fedora requires libQt6Gui.so.6(Qt_6.5_PRIVATE_API)(64bit), but none of the providers can be installed
  - cannot install both qt6-qtbase-gui-6.6.0-2.fc39.x86_64 from @commandline and qt6-qtbase-gui-6.5.2-5.fc39.x86_64 from @System
  - cannot install both qt6-qtbase-gui-6.6.0-2.fc39.x86_64 from @commandline and qt6-qtbase-gui-6.5.2-5.fc39.x86_64 from fedora
  - cannot install the best update candidate for package qt6-qtbase-gui-6.5.2-5.fc39.x86_64
Problem 2: problem with installed package qt6-qtsvg-examples-6.5.2-1.fc39.x86_64
  - package qt6-qtsvg-examples-6.5.2-1.fc39.x86_64 from @System requires qt6-qtsvg(x86-64) = 6.5.2-1.fc39, but none of the providers can be installed
  - package qt6-qtsvg-examples-6.5.2-1.fc39.x86_64 from fedora requires qt6-qtsvg(x86-64) = 6.5.2-1.fc39, but none of the providers can be installed
  - cannot install both qt6-qtsvg-6.6.0-1.fc39.x86_64 from @commandline and qt6-qtsvg-6.5.2-1.fc39.x86_64 from @System
  - cannot install both qt6-qtsvg-6.6.0-1.fc39.x86_64 from @commandline and qt6-qtsvg-6.5.2-1.fc39.x86_64 from fedora
  - cannot install the best update candidate for package qt6-qtsvg-6.5.2-1.fc39.x86_64

Problema 1: problema com o pacote instalado kf5-kwayland-5.110.0-1.fc39.x86_64    
  - não é possível instalar o melhor candidato à atualização para o pacote kf5-kwayland-5.110.0-1.fc39.x86_64    
  - nothing provides kf5-filesystem >= 5.111.0 needed by kf5-kwayland-5.111.0-2.fc39.x86_64 from updates-testing

sudo dnf5 up --enablerepo=updates-testing --best      
Updating and loading repositories:
Repositories loaded.
Failed to resolve the transaction:
Problem 1: cannot install the best update candidate for package kf5-kwayland-5.110.0-1.fc39.x86_64
  - nothing provides kf5-filesystem >= 5.111.0 needed by kf5-kwayland-5.111.0-2.fc39.x86_64
 Problem 2: package qt5-qtwebengine-freeworld-5.15.12-5.fc39.x86_64 requires qt5-qtbase(x86-64) = 5.15.10, but none of the providers can be installed
  - cannot install both qt5-qtbase-5.15.10-9.fc39.x86_64 and qt5-qtbase-5.15.11-3.fc39.x86_64
  - cannot install the best update candidate for package qt5-qtwebengine-freeworld-5.15.12-5.fc39.x86_64
  - cannot install the best update candidate for package qt5-qtbase-5.15.10-9.fc39.x86_64
 Problem 3: package qadwaitadecorations-qt6-0.1.2-5.fc39.x86_64 requires qt6-qtbase(x86-64) = 6.5.2, but none of the providers can be installed
  - cannot install both qt6-qtbase-6.5.2-5.fc39.x86_64 and qt6-qtbase-6.6.0-2.fc39.x86_64
  - cannot install the best update candidate for package qt6-qtbase-6.5.2-5.fc39.x86_64
  - cannot install the best update candidate for package qadwaitadecorations-qt6-0.1.2-5.fc39.x86_64
 Problem 4: package qadwaitadecorations-qt5-0.1.2-5.fc39.x86_64 requires qt5-qtbase(x86-64) = 5.15.10, but none of the providers can be installed
  - cannot install both qt5-qtbase-5.15.10-9.fc39.x86_64 and qt5-qtbase-5.15.11-3.fc39.x86_64
  - package kf5-akonadi-server-23.08.2-2.fc39.x86_64 requires qt5-qtbase(x86-64) = 5.15.11, but none of the providers can be installed
  - cannot install the best update candidate for package qadwaitadecorations-qt5-0.1.2-5.fc39.x86_64
  - cannot install the best update candidate for package kf5-akonadi-server-23.08.1-1.fc39.x86_64
 Problem 5: package obs-studio-libs-30.0.0~rc1-1.fc39.x86_64 requires qt6-qtbase(x86-64) = 6.5.2, but none of the providers can be installed
  - cannot install both qt6-qtbase-6.5.2-5.fc39.x86_64 and qt6-qtbase-6.6.0-2.fc39.x86_64
  - package qgnomeplatform-qt6-0.9.2-4.fc39.x86_64 requires libQt6Core.so.6(Qt_6.6)(64bit), but none of the providers can be installed
  - package qgnomeplatform-qt6-0.9.2-4.fc39.x86_64 requires qt6-qtbase(x86-64) = 6.6.0, but none of the providers can be installed
  - cannot install the best update candidate for package qgnomeplatform-qt6-0.9.2-1.fc39.x86_64
  - cannot install the best update candidate for package obs-studio-libs-30.0.0~rc1-1.fc39.x86_64
 Problem 6: problem with installed package 
  - package qadwaitadecorations-qt6-0.1.2-5.fc39.x86_64 requires libQt6Gui.so.6(Qt_6.5_PRIVATE_API)(64bit), but none of the providers can be installed
  - cannot install both qt6-qtbase-gui-6.5.2-5.fc39.x86_64 and qt6-qtbase-gui-6.6.0-2.fc39.x86_64
  - cannot install the best update candidate for package qt6-qtbase-gui-6.5.2-5.fc39.x86_64
 Problem 7: problem with installed package 
  - package qt5-qtwebengine-freeworld-5.15.12-5.fc39.x86_64 requires qt5-qtbase(x86-64) = 5.15.10, but none of the providers can be installed
  - cannot install both qt5-qtbase-5.15.10-9.fc39.x86_64 and qt5-qtbase-5.15.11-3.fc39.x86_64
  - package kf5-frameworkintegration-5.111.0-2.fc39.x86_64 requires qt5-qtbase(x86-64) = 5.15.11, but none of the providers can be installed
  - cannot install the best update candidate for package kf5-frameworkintegration-5.110.0-1.fc39.x86_64
 Problem 8: problem with installed package 
  - package qadwaitadecorations-qt5-0.1.2-5.fc39.x86_64 requires qt5-qtbase(x86-64) = 5.15.10, but none of the providers can be installed
  - cannot install both qt5-qtbase-5.15.10-9.fc39.x86_64 and qt5-qtbase-5.15.11-3.fc39.x86_64
  - package plasma-integration-5.27.8-2.fc39.x86_64 requires qt5-qtbase(x86-64) = 5.15.11, but none of the providers can be installed
  - cannot install the best update candidate for package plasma-integration-5.27.8-1.fc39.x86_64
 Problem 9: problem with installed package 
  - package obs-studio-libs-30.0.0~rc1-1.fc39.x86_64 requires qt6-qtbase(x86-64) = 6.5.2, but none of the providers can be installed
  - package obs-studio-libs-30.0.0~beta3-2.fc39.x86_64 requires qt6-qtbase(x86-64) = 6.5.2, but none of the providers can be installed
  - cannot install both qt6-qtbase-6.5.2-5.fc39.x86_64 and qt6-qtbase-6.6.0-2.fc39.x86_64
  - package qt6-qt5compat-6.6.0-1.fc39.x86_64 requires libQt6Core.so.6(Qt_6.6)(64bit), but none of the providers can be installed
  - package qt6-qt5compat-6.6.0-1.fc39.x86_64 requires libQt6Core.so.6(Qt_6.6_PRIVATE_API)(64bit), but none of the providers can be installed
  - package qt6-qt5compat-6.6.0-1.fc39.x86_64 requires qt6-qtbase(x86-64) = 6.6.0, but none of the providers can be installed
  - cannot install the best update candidate for package qt6-qt5compat-6.5.2-1.fc39.x86_64

This update breaks calibre, I can no longer open .epub files

[1020/000924.803262:FATAL:v8_initializer.cc(516)] Error loading V8 startup snapshot file

Also during installation it reports:

ln: failed to create symbolic link '/usr/share/calibre/mathjax3': File exists
warning: %posttrans(calibre-6.28.1-2.fc39.x86_64) scriptlet failed, exit status 1

Error in POSTTRANS scriptlet in rpm package calibre
  Running scriptlet: qt6-qtbase-common-6.5.2-5.fc39.noarch  

IMHO, it is unacceptable to deliberately push to stable an update known to break an application. It defeats the very purpose of the update testing process to knowingly push regressions reported here to stable.

At this point, we are not even talking about a development branch anymore, but about a 0-day update to a stable release. There ought to be a minimum quality standard for such an update. There is also no deadline to hit given that the release is already in Final Freeze.

Similar to @tseewald's feedback above, someone reported that my eric update FEDORA-2023-af95a99daa was failing, and I confirmed that this only occurs in conjunction with this update, but not with Qt 6.5.2 in F39 stable. Both calibre and eric use python-pyqt6-webengine, and "V8" in the error message points in that direction as well. I suspect this is an incompatibility between PyQt6/PyQt6-WebEngine 6.5 and Qt/QtWebEngine 6.6. Do we know if upstream PyQt6 6.6.0 releases are imminent?