Pretty sure this is fixed on Files 3.26 on Ubuntu 17.10. If you can reproduce the bug on a supported Ubuntu release (14.04, 16.04, or 17.10) or the development release (18.04) then, if the former, please post asking for the bug to be marked as affecting the relevant series (e.g. Xenial (for 16.04)) or, if the latter, please change the bug's status to 'New' and report upstream at https://gitlab.gnome.org/GNOME/nautilus/issues (though it's a problem that I'm unable to reproduce it).
** Changed in: nautilus (Ubuntu) Status: New => Fix Released -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1513063 Title: trouble setting file association To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/nautilus/+bug/1513063/+subscriptions -- ubuntu-bugs mailing list firstname.lastname@example.org https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs