I right-clicked on the panel at the bottom of the screen > Troubleshoot > Restore all settings to default. The reason I did that: there was a big gap between the add/remove icon and the other icons.
After the restore, KeepassXC does not launch anymore when I click on it in the main menu.
Yepp, the first thing to do when a program refuses to launch is to try and launch it from the terminal. Usually you’ll get some errors in the terminal explaining why it won’t launch.
In a 1st effort it said “another instance of keepassxc is already running”. So, to stop that instance via the terminal I had to find out its PID doing “pidof keepassxc”.
Then, I could stop that via the terminal using “sudo kill -9 ”. Restarting Keepassxc via the terminal then worked, there were no errors shown.
Launching it from the menu thereafter also worked.
Thank you.
BTW, I am sure you know the steps I wrote above, I just added them for completeness sake if ever someone else stumbles upon this page.
I just added to what pycrk has said (and tryed to make it into a more general response) because I totally agree with his proposed solution. Credit should go to him.