@P-Baumgart: there is a workaround, start Firefox from a terminal as follows (or create a little shell script that starts firefox like that):
LANG=C firefox
That will run Firefox in US English (the problem is with the translations).
@sunblade: that is not the same error of course, but maybe it's caused by the same or a similar bug in the system that converts Launchpad translations to Mozilla format translations...
@P-Baumgart: there is a workaround, start Firefox from a terminal as follows (or create a little shell script that starts firefox like that):
LANG=C firefox
That will run Firefox in US English (the problem is with the translations).
@sunblade: that is not the same error of course, but maybe it's caused by the same or a similar bug in the system that converts Launchpad translations to Mozilla format translations...