I tried editing my display name and for some names it gives me this error:

Display Name can only contain a-z, 0-9, spaces, apostrophes or hyphens and must start with a letter or number

That is clearly not the case, because it will take the following names:

  • NullUserException -龍-
  • NullUserException Ω
  • NullUserException ఠ_ఠ
  • NullUserException ಠ_ಠ
  • NullUserException இ_இ

But it won't let me do:

  • NullUserException (╯°o°)╯
  • NullUserException ٩๏̯͡๏)۶
  • NullUserException ☜(゚ヮ゚☜)
  • NullUserException อ้_อ้

So what's the regex used (assuming that's what's being used), so I can try out allowed names without actually changing it?

  • 2
    bug post: Error message misrepresents available characters for display name
    – Jeremy
    Commented Sep 15, 2011 at 23:41
  • 20
    Yeah, I tried changing my name to the guy flipping the table over and it didn't work for me either. If you can't have an ascii guy flipping a table over as your username what is the whole point of the site anyway?
    – Pollyanna
    Commented Sep 15, 2011 at 23:46
  • 1
    I saw "NullUserException ヮ゚" for your username when viewing this from the front page. Commented Sep 15, 2011 at 23:46
  • 1
    @Andrew It's because I've been messing with my display name Commented Sep 15, 2011 at 23:47
  • 1
    How did you manage to try out all the valid user names without running into the 30-day limit?
    – Pekka
    Commented Sep 16, 2011 at 8:34
  • 4
    @Pekka - you can change it on each site and then copy the name to all the other sites.
    – ChrisF Mod
    Commented Sep 16, 2011 at 9:21
  • @ChrisF yeah, I forgot. That was probably how he did it.
    – Pekka
    Commented Sep 16, 2011 at 9:26
  • 1
    @Pekka It actually lets me try out a bunch of different display names. I think there's a kind of "grace period" where I can change the name as many times as I want Commented Sep 16, 2011 at 13:59
  • Try this one - ノ'o'ノ丄丄 Commented Feb 14, 2015 at 23:33

1 Answer 1


a-z includes unicode characters, the way we define it.

So essentially the character set that maps to \w in a .NET regex.

  • 29
    You have an... interesting... definition of a-z. May I suggest "alphanumeric characters", or "letters, numbers, or..."? Commented Sep 16, 2011 at 5:07
  • 10
    They made one of the classical Unicode Regex errors!!! Now we should try finding a numeric field and writing ৩০ for the age!!! (it's 30 in Bengali Digits. \d will conside them digits, Int32.Parse won't)
    – xanatos
    Commented Sep 16, 2011 at 8:41
  • 1
    @MichaelPetrotta status-completed
    – user154510
    Commented Sep 16, 2011 at 15:38
  • 6
    May I respectfully request that it follow the Unicode Consortium’s recommendation of the \w definition of word characters according to Annex C of UTS #18 on Unicode Regular Expressions? Also, what is the length restriction in characters?
    – tchrist
    Commented Aug 11, 2012 at 0:40

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