This question already has an answer here:
I got the following error:
Oops! There was a problem updating your profile:
- Display Name can only contain letters, digits, spaces, apostrophes or hyphens and must start with a letter or digit
after I tried to set my username using Japanese letters:
Which of them cannot be used?
I cannot try every letter to see if it pass the validation because I cannot save my username again, then.