After upgrade to firefox 71 I can only open links from some applications
I'm on Fedora 31. Firefox was recently upgraded to 71.0 and I find a weird pattern in trying to open links from applications - possibly related to Slack:
If firefox was initially opened following a link from Slack, I can open other links from Slack, but trying to follow links from other applications (IBM Lotus Notes, or running "firefox URL" from a terminal window) fails with a "Firefox is already running" message.
If I open firefox from the desktop applications menu, the reverse happens. I can open links from Notes and a terminal, but following links from Slack fails.
I tried reinstalling firefox and slack with no success. Today I tried going back to an earlier version - firefox-70.0.1-4.fc30.x86_64.rpm - and everything seems to be okay.
It seems like something changed in firefox 71 that doesn't play well with Slack.
I found a work-around. Add this to ~/.bashrc, then log in again.
You might also be able to install firefox-x11 and make that the default browser. I have many personal bash scripts that open URLs via 'firefox URL'. I probably ought to be using 'xdg-open URL'.
Until then - or until the issue is fixed - this gets me going.
I found that I had an old ~/.local/share/applications/slack.desktop file that launched Slack using: Exec=env XDG_CURRENT_DESKTOP=Unity /usr/bin/slack %U
Other apps have an environment with XDG_CURRENT_DESKTOP=GNOME, which I believe is correct.
I copied /usr/share/applications/slack.desktop over the .local file. That seems to have fixed it.