Just came across this. If you get a language not allowed error in the app when trying to post, it could be a mismatch between the language in the user profile and the community language. I discovered this while trying to comment on a community I am a mod in and kept getting denied (my profile language remains ‘undefined’ and the community had English selected only - guess I got overzealous).
My takeaway from this is to keep the ‘undefined’ language tag in communities just to be on the safe side.
I usually have kept “undefined” as a language for communities, with the exception of [email protected] and [email protected].
lesson learned for me… the hard way
And to add, those two communities have languages set because I want the first one to be purely in Finnish and the second one purely in English. This mirrors how it is on Reddit.
