User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Firefox/60.0 Build ID: 20180503143129 Steps to reproduce: In Debian, I run Firefox 60 from terminal logged in as "su -". Actual results: A message¹ displayed and Firefox does not launch. ¹Running Firefox as root in a regular user's session is not supported. ($XAUTHORITY is /home/sm01/.Xauthority which is owned by sm01.) Expected results: Firefox is launched as root as usual (version 59.x allowed this). This is because of bug #1323302 but the the question is now what's the recommended way to run Firefox as root. I need to run Firefox with admin privileges in order to perform an easy update from menu because the application is installed globally under /opt so no user can update the brower but root. Yes, I can still udpate it manually by getting the partial ".mar" files but this is a bit tedious.

There is no recommended way to run Firefox as root, and because of our sandboxing techniques it's quite broken even if we hadn't explicitly disabled it through start-up checks. As a "bug" this is not something we're going to fix. "Run Firefox as root" doesn't seem to be your ultimate intention though, more like "How do I manage a shared Firefox installation so it gets updates?" That sounds like a support question rather than a bug. I don't actually know that answer--I don't use a shared machine or multiple accounts so I just install locally--but you can try our support site https://support.mozilla.org/ or our forums https://www.mozilla.org/en-US/about/forums/ or maybe even StackOverflow once more people run into this issue.

Actually you should still be able to --Log In-- as root and run Firefox, just not su -

Just for the record, these two ways do still work: 1/ Full X session login (as root) and launch Firefox from there, but this option should be discouraged. 2/ If SSH if available (up and running) "ssh -X root@localhost" also works.

With the release of Firefox 60ESR, we have new paths for supporting deployments across organizations: https://www.mozilla.org/en-US/firefox/organizations/

Thnaks for the comments and ideas but not such case, here (single user on system).