Thanks for reaching out - Based on the error message I'm seeing, it looks like Zitadel is having trouble parsing a language tag you've provided during the auth flow. Can you give me more insight into which external idp you're using?
@m20 Could you possibly share the response you received from your custom IDP? Please obscure any private data! Can you also give me some more insight on the application you're trying to connect to?
@m20 Take a look at the latest responses in this thread and let me know if this helps! If not, could you share the version of Zitadel that you're using if you're self-hosting?