ok, so it used to work and it stopped with 18.0.2 at least (I'm not sure which version was the last one) The prefrenses file should be updated: $filesdir/firefox-bin-prefs.js The new parameters are: user_pref("app.update.auto", false); user_pref("app.update.enabled", false); Please verify it first
*** This bug has been marked as a duplicate of bug 434542 ***