Try running the following in a terminal. I had the same problem and this worked for me.
sudo apt-get install dbus-user-session
systemctl --user start dbus.service
cd ~
mv .mozilla .mozilla_backup
mv snap/firefox snap/firefox_backup
firefox
Edit: at this point, your thermal printer probably doesn’t work either. You’ll need to apply this fix and restart cups (or just reboot, I guess).