Thanks for adding the error message. I'm afraid don't know what goes wrong, all I could find when searching for the error message was an ancient bug report (bug 1191700) which I don't know if is relevant or not. Setting status back to New, hopefully someone else can take a look at this and see what's going on.
** Changed in: software-properties (Ubuntu) Status: Incomplete => New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1961477 Title: software-properties-gtk not running To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/software-properties/+bug/1961477/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs