Plasma 6: Application Menu Does not Refresh List when Applications added/removed

[Lyndeno]

Describe the bug

When applications are added or removed, the menu stays with the current list from when I originally installed Plasma. Reboots or restarts does not refresh it.

Steps To Reproduce

Steps to reproduce the behavior:

1. Install Plasma
2. Add or remove applications (in my case within nixos config)
3. Menu keeps old list

Expected behavior

Application menu refreshed with current available applications

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[Naxdy]

The problem seems to be that when a new ksycoca6_..... file is created in the ~/.cache, plasma just completely ignores it and happily continues to use whichever one it has been using. A workaround (for now) is to manually run rm ~/.cache/ksycoca* (or add it to your activation scripts, lol) after every nixos-rebuild, and this should take care of things.

Still, it'd be nice to know if this is a NixOS issue, or an upstream issue. Feels like it could be either?

[nixos-discourse]

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/enable-plasma-6/40541/7

[reasonings]

A workaround (for now) is to manually run rm ~/.cache/ksycoca* (or add it to your activation scripts, lol) after every nixos-rebuild, and this should take care of things.

When I add it to my activation scripts, it does remove it, but it never comes back. All icons go blank and the only way to get them back is to reboot.

[pbek]

Does a plasmashell replace help?

[K900]

So there are actually multiple issues here. Most KDE applications pull their knowledge of currently available apps from a shared cache called sycoca (for SYstem COnfiguration CAche), which is maintained by KService. Unfortunately, it does not work correctly on NixOS for multiple reasons:

1. The cache can be rebuilt in-process, by each application, but the name and contents of the cache depend on XDG_DATA_DIRS, which is different for many processes due to wrappers, so we end up with multiple unrelated copies of the cache, each maintained by a different application, with a different view of things. This isn't necessarily an issue when the cache is updated correctly, except wasting a whole bunch of cycles.
2. The cache is updated by checking the mtimes on the target files, which for us are always 0, so the cache is effectively never refreshed unless nuked entirely. The solution to that is probably to make KService actually walk up the path until it finds a symlink to the store, and then check the mtime of that, but that's an extremely invasive change.

#292748 should unblock us for now by restoring the nuke-all-sycoca activation script from Plasma 5, but we'll definitely want to look into some kind of a better solution going forward, and probably get upstream involved.

[K900]

Can people affected by this please test #292748 ?

[JonathanBrouwer]

For me running xdg-desktop-menu forceupdate fixes the problem as well, so as a workaround I added that to my rebuild script

[ShalokShalom]

I had the same issue with NeoChat and was informed, that this fix corrects the issue and indeed, after an update and reboot, it showed up.

[NovaViper]

Can people affected by this please test #292748 ?

I'm still plagued by this issue, neither installing kcmutils nor the nuke script functions on my system (My lock file has nixpkgs at 73d699a). Anytime I rebuild my system with nixos-rebuild switch or nixos-rebuild test, it refreshes the list but I can't click on any of the icons and no apps open until either I restart the system or log out. Even the icons pinned to my task manager disappear aswell

My flake: https://github.com/NovaViper/NixConfig

[sdellysse]

I'm still seeing this issue. I run nixos-rebuild switch and now when I click on apps in my KDE "Start Menu", nothing happens. Running latest nixos-stable, updated and rebuilt this morning

[pbek]

Do you have this issue in the "Favorites" part of the menu? (because I even have that issue under Plasma 5)

[Shawn8901]

I can confirm for the Favorites. Normal menu items do work for me in the meantime totally fine.

[pbek]

Ok, I guess then that's a general Plasma5/6 issue on NixOS. 😅
Is this worth a new issue, @K900?

[K900]

I have not observed this issue on 6, at least.

[pbek]

Strange... I just tested it after a QOwnNotes update in the morning on a Plasma 6 Laptop. 🤔
I can search for it or use the normal menu entry from the different categories, but the favorite entry can't be clicked.
And it's the same on Plasma 5 for me.

I can't even right-click and "Edit application..." those entries that got an update.
If I remove the favorite and add it again, I can click it again too.

[micmalti]

I've noticed the same issue in KRunner when doing an app search. Currently on Plasma 6.0.5.

[K900]

It has been mostly fixed on nixos-unstable, a proper fix would require some major changes to the internals of kservice.

[tazihad]

Fedora 41 KDE plasma has this issue. Although restoring it brings the icons. So, I guess nix need to refresh KDE plasma start menu.

[Red-M]

I've got this issue and I installed my NixOS within the last week.
Using stable and I get the same issues, the favourites section of plasma doesn't launch anything and I also can't edit them after a nixos-rebuild if the packages get changed.

[K900]

This should be mostly worked around in 24.11.