On your system, find the .desktop
launcher files containing the text Name=Software Install
. Inspect their contents and see what program they launch on the Exec=
line. You can execute that command manually in the terminal to see which one is the one you want to keep. Delete the other one.
I suspect that you may have two software centers, the default Ubuntu Snap Store, which is installed as a snap package, and an additional "Gnome Software", installed as a regular APT package.
Another suspicion is that it is the Snap Store that does not work and the reason could be that the .deb
file you try to install is not in a directory in which that snap package has access.
If indeed you can confirm that you have these two software centers installed, then you can test which one works for you and which one not:
snap-store.ubuntu-software-local-file --local-filename <path to your deb file>
sudo gnome-software --local-filename <path to your deb file>
If you wish, remove the one that does not work. The commands are sudo snap remove snap-store
and sudo apt remove gnome-software
.
It could be the Snap store that is not working, and that then could be because the .deb
file you try to install is not in a directory in which that snap package has access.