Sometimes I get this error message when I try to post a comment, then I just cant comment under that post at all. On other posts it does work like it should. I have checked the language settings and they are set proberly. Is this a Voyager-problem or a Lemmy-problem?
This is a Lemmy problem. Some communities only allow certain languages. For some reason, some posts and comments can get through on an unsupported language. For example comments from Kbin come through as an Undetermined language (despite have the language selected in Kbin). When you try to reply to these posts or comments, Lemmy will automatically set your reply in the same language, if it is unsupported by the community, you will get this error.
If you go directly to your Lemmy web page (not in Voyager) and try to reply, the Post button will just spin indefinitely. To post successfully, you will need to specifically enter the language in the selector below your comment.
There has been a patch to fix it in Lemmy, but I’m not sure when that will filter done to our instances. Voyager are tracking the issue here.