German special characters not allowed in usernames

how can I allow german special characters (ö,ä,ü & ß) in the user registration?

In German-speaking countries, surnames like “müller” are quite normal.

Do you have any function for the childtheme to solve this problem? Thanks a lot


We use the WordPress function for this sanitize_user() | Function | WordPress Developer Resources. So, unfortunately, there is no easy solution to change this. But thanks for your suggestion; we’ll consider adding this feature.


Thank you for the information. It’s a pity that it doesn’t work at the moment and I hope you could implement something like that in a future update.

Kind regards

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