However, when trying to use non-ASCII characters (like é or ç) in user names, the validation check fails with the error message "Required, 255 characters or fewer. Only letters, numbers, and @, ., +, -, or _ characters."
There does not appear to be a closed or open Issue related to non-ASCII characters in user names. This would suggest that non-ASCII characters are in fact not allowed in user names and this 21.1 test check should be eliminated.
However, when trying to use non-ASCII characters (like é or ç) in user names, the validation check fails with the error message "Required, 255 characters or fewer. Only letters, numbers, and @, ., +, -, or _ characters." There does not appear to be a closed or open Issue related to non-ASCII characters in user names. This would suggest that non-ASCII characters are in fact not allowed in user names and this 21.1 test check should be eliminated.