Firefox thinks it's already running

[roemer2201]

Dear All,
I run multiple machines with Ubuntu 22.04, on them I removed the Firefox snap and installed it as a .deb from the official Mozilla-Repo. The instructions can be found here:

• https://askubuntu.com/questions/1399383/how-to-install-firefox-as-a-traditional-deb-package-without-snap-in-ubuntu-22
• https://www.omgubuntu.co.uk/2022/04/how-to-install-firefox-deb-apt-ubuntu-22-04

With this setup, PSD enabled and running, Firefox won't start and pops up a message "Firefox already running, but not responding." This is what ps aux | grep firefox looks like, if PSD is stopped:

username   46511 27.0  1.6 3044608 388524 ?      Sl   12:21   0:03 /usr/lib/firefox/firefox
username   46587  0.2  0.1 214460 45312 ?        Sl   12:21   0:00 /usr/lib/firefox/firefox -contentproc -parentBuildID 20231211174248 -prefsLen 30550 -prefMapSize 234204 -appDir /usr/lib/firefox/browser {132bea7d-22a7-48e8-af21-c141984bfab2} 46511 true socket
username   46608  7.2  0.6 2479432 151076 ?      Sl   12:21   0:00 /usr/lib/firefox/firefox -contentproc -childID 1 -isForBrowser -prefsLen 30691 -prefMapSize 234204 -jsInitLen 229864 -parentBuildID 20231211174248 -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appDir /usr/lib/firefox/browser {f67f090d-057a-4430-9860-96ec87172447} 46511 true tab
username   46668  3.4  0.4 2447860 111236 ?      Sl   12:21   0:00 /usr/lib/firefox/firefox -contentproc -childID 2 -isForBrowser -prefsLen 36059 -prefMapSize 234204 -jsInitLen 229864 -parentBuildID 20231211174248 -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appDir /usr/lib/firefox/browser {d6d42925-a396-41cc-8fd1-deac3819b76a} 46511 true tab
username   46721  0.6  0.1 213024 40960 ?        Sl   12:21   0:00 /usr/lib/firefox/firefox -contentproc -parentBuildID 20231211174248 -sandboxingKind 0 -prefsLen 35773 -prefMapSize 234204 -appDir /usr/lib/firefox/browser {5dbe473b-03b1-4847-afe2-e0fc8e9f378b} 46511 true utility
username   46724  1.0  0.3 2398920 79360 ?       Sl   12:21   0:00 /usr/lib/firefox/firefox -contentproc -childID 3 -isForBrowser -prefsLen 29487 -prefMapSize 234204 -jsInitLen 229864 -parentBuildID 20231211174248 -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appDir /usr/lib/firefox/browser {c2e33c96-4004-4733-b2c2-973c84bdb490} 46511 true tab
username   46737  0.9  0.3 2398920 79360 ?       Sl   12:21   0:00 /usr/lib/firefox/firefox -contentproc -childID 4 -isForBrowser -prefsLen 29487 -prefMapSize 234204 -jsInitLen 229864 -parentBuildID 20231211174248 -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appDir /usr/lib/firefox/browser {d81e4b8f-5bb9-4247-97f5-278cb727ba06} 46511 true tab
username   46739  1.0  0.3 2398920 79232 ?       Sl   12:21   0:00 /usr/lib/firefox/firefox -contentproc -childID 5 -isForBrowser -prefsLen 29487 -prefMapSize 234204 -jsInitLen 229864 -parentBuildID 20231211174248 -greomni /usr/lib/firefox/omni.ja -appomni /usr/lib/firefox/browser/omni.ja -appDir /usr/lib/firefox/browser {f13d6b9c-2217-4b20-9ff8-870fec15c600} 46511 true tab
username   46779  0.0  0.0   9604  2560 pts/0    S+   12:21   0:00 grep --color=auto firefox

psd --version reports Profile-sync-daemon v6.34 on Ubuntu 22.04.3 LTS.

Is there something I can do about it?

Thank you in advance!

[roemer2201]

I just discovered that apparmor blocks (e.g.) firefox from accessing files in many places of the root-filesystem. I thought this might be helpful, maybe apparmor also blocks access to /run/user , where the temporary profiles are stored.