Before I go any further, let me begin by saying that this problem is solved, so this is more of a war story and cautionary tale than anything else.
TL;DR: Hyprland was not officially included in Fedora 42 so I used an external repository to install it. This completely broke my KDE installation after a seemingly-smooth upgrade to 43.
As some of you know, over the last few months I have been playing with (and eventually dropping) the Hyprland window manager. Because Hyprland was not a native part of Fedora 42 I used an external, non-supported repository. Most Linux systems that use package managers allow for the use of such repositories. In Fedora it's known as COPR, in Ubuntu they're "PPAs" and in Arch it's the well-known AUR.
I have no usable experience with Arch. But when I used to rely on Ubuntu, one of the first things that happened automatically during a major update was the disabling of all PPAs. This makes sense. However, the Fedora 43 update now *added* Hyprland in its main repositories but did not disable my COPR that had previously provided it. Not only did this screw up my Hyprland installation, but also kept KDE from installing properly either. I had error messages such as
file:///usr/share/plasma/plasmoids/org.kde.plasma.kickoff/contents/ui/main.qml:21:1: Cannot load library /usr/lib64/qt6/qml/org/kde/plasma/private/kicker/libkickerplugin.so: /lib64/libKF6Runner.so.6: undefined symbol: _ZN14KWaylandExtras18xdgActivationTokenEP7QWindowRK7QString
My fix, once I thought this might have something to do with duelling hyprlands, was to:
1. Mabually sisable the relevant COPR entry
2. Remove hyprland and autoremove its dependencies
3. Clean and re-sync the package cache
4. Re-start the upgrade
5. Re-install hyprland (optional, and I didn't bother)
Maybe someone can convince Fedora that disabling COPRs during a major upgrade would be a Good Idea, following Ubuntu's practice in disabling PPAs..
- Evan