Okay. It's a pity. But anyway, thank you very much.
Maybe some further version will work on my server, too

I just installed the nightly build and things are working fine.
Thank you.

I just ran into this - it freaked me out, then I realised that in the language options I needed to check 'English (United States)' in addition to using the HTTP accept language (I had unchecked them previously). Perhaps on the server I'm using the language isn't specified or something.

There is a tool on our troubleshooting to check which locales your server has installed. Since langauges depend on the locale available (if you want to use e.g Spanish you need the Spanish locale on the server - this is a server thing).