This is a very old version of firefox that you have indeed. It looks like you haven't installed neither regular nor security updates. I strongly recommend enabling them: launch "Software & Updates", click on the "Updates" tab, and check the "xenial-security" and "xenial-updates" checkboxes, then install all the available updates.
Using a system without security updates is not recommended if it is connected to the internet. ** Changed in: firefox (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1873062 Title: I'm unable to update firefox To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1873062/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs