Reopened because this is happening out-of-the-blue again. It may be because of the last round of updates. Once again, "sudo dpkg --purge --force-all firefox" then "sudo apt-get install firefox" fixed it.
Reopened because this is happening out-of-the-blue again. It may be because of the last round of updates. Once again, "sudo dpkg --purge --force-all firefox" then "sudo apt-get install firefox" fixed it.