After further investigation, the bug is in Gedit (or GTK?), not in Firefox: I have noticed that, when the bug occurs, I cannot paste (the data copied from gedit) in LibreOffice either. If I close gedit and open it again, I can copy / paste from Gedit to Firefox (or LibreOffice) again.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1915498 Title: Copy / paste in Firefox randomly broken To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1915498/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs