I tried to update Firefox Snap (from 100 to 101):
sudo snap refresh firefox
but I got a message that an update was pending, but it could not update because Firefox was running an app, although I did close all Firefox windows and I couldn't find anything with pgrep firefox
After a reboot, the update command was working.
So, how do you update Firefox on Ubuntu 22.04 without restarting the system?
I had a similar issue, but I was simply being neglectful about closing Firefox.
However, I recommend using something like
pkill firefox
orkillall firefox
in the future to see if that'll close all instances of Firefox to stop it from complaining.