Kubuntu 26.04 Upgrade Issues

03 May 2026

I recently upgraded to Kubuntu 26.04 from 25.10 and encountered several major issues. Note that Kubuntu 26.04 isn’t yet offered as an upgrade path yet, so I used the sudo do-release-upgrade -d method to test as an early adopter.

Note: I don’t like to upgrade from the GUI to minimize the software I have running. So while logged out of KDE I used a VT (ctrl-alt-F3) to login to a terminal and run the command. I don’t know of any benefit to this besides satisfying my own paranoia on upgrading KDE while it is running.

Now there are plenty of good reasons to upgrade, kernel 7.0 and KDE 6.6 as starters, but this is covered well online, so I’ll only mention my issues. I’m still happy I upgraded and the issues took me only a few hours to resolve, but I’m still worried that Linux is not “ready” for non-technical users. For non-technical users my advice is to wait a while before upgrading to any new Ubuntu release, even LTS ones. I suspect most of the issues below will get fixed, although some are probably unavoidable, like the device renaming impacting input-remapper.

grub-efi-amd64-signed failed to upgrade

• Issue: grub-efi-amd64-signed failed to upgrade with error special device /dev/disk/by-id/... does not exist.
• Resolution: For whatever reason, my EFI partition had msftdata flags. I used gparted to set boot and esp flags. Then I could run sudo dpkg --configure -a
• Details: I suspect this was caused from the period where I had both Windows and Kubuntu installed in a dual-boot configuration, although I got rid of Windows entirely about a year ago.

input-remapper issues

• Issue: input-remapper stopped working for my mouse. The device’s name changed, possibly due to the new Logitech specific support from kernel 6.19.
• Resolution: I copied the JSON file from the old name to the new name in ~/.config/input-remapper-2/presets/, then I could trigger autoload for it.
• Details: Google says the folder should be ~/.config/input-remapper/presets/. I’m not sure why mine is as -2, so try either path, or you can just recreate your presets from scratch.

Mousewheel issues with G502X Logitech Mouse

• Issue: My G502X Logitech with Lightspeed receiver mouse wheel scroll barely registers any movements (3 clicks to 1 line). Changing scroll speed in KDE system settings does nothing.
• Resolution: In Solaar, I enabled the “Scroll Wheel Resolution” setting (thanks to Gemini’s advice). Solaar is a non-default app that I was already using that can be installed via sudo apt install solaar to manage Logitech devices.
• Deep Dive: Installing libinput-tools and running sudo libinput debug-events you can see the scroll events generated. If you don’t want Solaar or this issue affects your non-Logitech mouse, Gemini said there is a way to configure libinput to ignore the “REL_WHEEL_HI_RES” events. Also, this, like my earlier issue, I suspect is related to the new kernel 6.19 specific functionality for Logitech Lightspeed mice.

Disabled extra apt sources (common issue)

• Issue: Software from third party apt sources no longer updates. This is by design for Ubuntu/Kubuntu upgrades.
• Resolution (GUI): I didn’t try this, but I am told that in the software update tool (Discover) if you go to settings, you can simply re-check the disabled sources for those that are not specific to Kubuntu versions (in my case VS Code, Vivaldi, and Kopia).
• Resolution (CLI): The old files/lines will be disabled in /etc/apt/sources.list.d/ and (less common today) /etc/apt/sources.list. You may need to remove Enabled: no lines or make other updates. Once you do that, apt update and apt upgrade should work again.
• Details: I hate this common issue because there’s no warning that the upgrade tool does this, and you would find you stop getting updates to 3rd party installed code (in my case, Kopia, VS Code, and Vivaldi).

Obsidian snap fails to launch

• Issue: Obsidian installed via snap no longer launches. Others online have reported the same in Obsidian forums.
• Resolution: I already have Flatpak installed, so I just switched to that version. However, I suspect Obsidian and/or Ubuntu will release a fix.

Lost Kopia Repository

• Issue: Kopia can no longer backup to Google Drive
• Resolution: Recreated repository
• Details: I can’t imagine how this is related to the Kubuntu upgrade, especially as Kopia is installed from its own apt repository. However, the timing is odd. In Google Drive, the folder was 48MB, but the expected size was around 600MB. I’m worried it may have been broken before the upgrade, but KopiaUI wasn’t proactively warning me.

Temporary “Language support is incomplete” Notification

• Issue: “Language support is incomplete” notification from KDE. It asks to install gimp-help-en and language-pack-gnome-en. When I click install, I get a dialog that says “Package not found” and the installation fails.
• Resolution: Do nothing? After rebooting since fixing my earlier mentioned EFI issue, I got the prompt again, and it worked (after requesting sudo password).