Since upgrading to Kubuntu 26.04 LTS, images are no longer displayed

[greenster]

I would like to let you know that I have had to start all over again.

I created a USB stick with Kubuntu 26.04 LTS, wiped the internal hard drive and reinstalled Kubuntu.

File previews are now displaying correctly.

Thank you for your professional help, especially to @Schwarzer Kater

[greenster]

I ran this code again and the result was tty5. Is that a good or bad sign? I still can't see any previews.

How can I clear the cache in Kubuntu?

[ShadYoung]

I have noticed the same thing on my desktop, but not within folders. After restarting my computer, they all showed up again.

[Schwarzer Kater]

[…]
There was a bug a year ago for x11 only.
https://bugs.kde.org/show_bug.cgi?id=503799

Just my two EuroCents: I don't think this is an X11 problem.
I am using both X11 and Wayland (fresh 26.04 installation) and everything works everywhere regarding image previews - doesn't matter whether old images or images I just created…

[greenster]

systemsettings -> default applications -> file associations what does it list for .png?

See here:

[life0riley]

This is an upgrade I can see from the subject line.
Are you using Wayland or x11?
What is the output of:

echo $XDG_SESSION_TYPE

The output looks like this on mine:

$ echo $XDG_SESSION_TYPE
wayland
$​

There was a bug a year ago for x11 only.
https://bugs.kde.org/show_bug.cgi?id=503799

[Schwarzer Kater]

Schwarzer Kater I’ve now managed to follow your instructions successfully, but now my old images – the ones I created before the upgrade – are no longer visible either.

I am really sorry to hear that…

It seems something has been seriously broken by your do-release-upgrade -d from 25.10 to 26.04.

The final thing I (personally) would try is to create a new user account with administrator privileges ( -> System Settings -> Users (section: System) ) and test if the problem is still there. If no: transfer your data to the new user account and don't think about it anymore.
If yes - the problem also is there in a new user account: I (personally) would not waste any more time, but backup my data, erase the old system and start a fresh installation of Kubuntu 26.04…

[greenster]

I haven’t changed anything since I followed your instructions to upgrade to Kubuntu 22.04 LTS.

Is it possible to completely reset Dolphin?

[sgmoore]

systemsettings -> default applications -> file associations what does it list for .png?

[life0riley]

I had one that was [Ctrl] [Alt] [F7] in one of mine. I can't remember the OS.
I have to step away for an hour, but will be following. I'm interested to see if clearing the cache worked.

[Schwarzer Kater]

jlittle :

I was a bit unsure myself, but had tested it before posting.

I have tested this two more times:
SDDM seems always to be on tty1 now, hence [Ctrl] [Alt] [F1].
The GUI is somewhere between tty2 and tty4 after one has logged in.

Don't ask me why, I am confused…
They must have changed something in Kubuntu 26.04 compared to the releases before.

[greenster]

Schwarzer Kater I’ve now managed to follow your instructions successfully, but now my old images – the ones I created before the upgrade – are no longer visible either.

[jlittle]

-> press [Ctrl] [Alt] [F1] -> you should see the graphical log in screen (SDDM) again -> log in with your user account

That's ctrl-alt-f2 on my desktop (with 25.10). ctrl-alt-f1 shows the boot messages.

[Schwarzer Kater]

These are "single commands", you have to enter them separately - just a moment, I will alter my post accordingly… OK. Please reload this page now.

And no spaces in between where there are none in my post! Enter them exactly as I posted in the commands, please - a space at the wrong place and you could erase your system!
There are single spaces directly behind sudo, cd, rm and -r -> nowhere else.

[greenster]

Thank you very much for your help, but I’m afraid I’m stuck here: