Update
My problem is partly solved.
After searching dozens of webpages for hints I found one for my second problem
that Gimp (snap) is not visible in my program starter. Other snaps were visible!
There "sudo apt install gnome-software-plugin-snap" was recommended.
I tried but Gimp was still
Public bug reported:
I upgraded from 18.04 LTS to 20.04 LTS.
That needed many hours.
Afterwards I ovserved a strange behaviour:
1) The desktop icons fail.
- if I'm clicking on computer, network or trash I get "unknown filetype"
- if I'm clicking on home or a mounted drive instead of a file
*** This bug is a duplicate of bug 1760201 ***
https://bugs.launchpad.net/bugs/1760201
** This bug has been marked a duplicate of bug 1760201
ubuntu 18.04 GDM - missing icons and letters on login screen with nouveau +
Wayland
--
You received this bug notification because you are a
Reinstalling ubuntu-desktop didn't change anything.
So I tried to find other posts with the same problem.
It seems my English was not good enough to use the best keywords in the
previous searches. But this time I found something new:
Thank your for the fast answers.
I have to admit I am just an Ubuntu user not an expert, so your recommendations
were difficult for me.
What would "startx" do? My login screen is strange, but afterwards
graphical desktop is running.
In another thread I found for "reinstall ubuntu":
sudo
Public bug reported:
After updating to Ubuntu 18.04 LTS the login screen shows no user names, just
the user icons.
In the follow up screen some letters are missing e.g. "Cancel" is written "Ca
l ", see screenshots.
https://www.pic-upload.de/view-35312811/ubuntu18.04.login-screen.png.html
If
