Comment 88 for bug 1951491

Thanks for your comments and workarounds, I was using nomachine at a headless server with run target set to multi-user instead of graphical, and Firefox had this problem in the xsession created by nomachine.

My workaround is to edit the Firefox script itself, handily, /usr/bin/Firefox is a script instead of a binary, so I added

unset DBUS_SESSION_BUS_ADDRESS

towards the end of the script just before the last line calling presumably the Firefox binary.

Works like a charm, and feels good to know that only Firefox will be affected in case other programs need the DBUS_SESSION_BUS_ADDRESS to function properly.

Hope it helps.