I need to create 3 logins on a SQL Server 2005 instance:

  • DOMAIN\aaa
  • DOMAIN\bbb
  • DOMAIN\ccc

However two of them (aaa and bbb) fail with the following error:

Msg 15401, Level 16, State 1, Line 5 Windows NT user or group 'DOMAIN\aaa' not found. Check the name again.

When I try to add them with DOMAIN\AAA and DOMAIN\BBB it works.

What is causing this strange case sensitive behaviour? And how can I add all accounts lower case?

I found a KB article from Microsoft for the 15401 error, but nothing in there explains this behaviour.

  • I had the same issue once. I think I was able to change the collation at the DB level and this fixed the problem. Let me check the server again, and I will let you know. Aug 23, 2011 at 1:10

1 Answer 1


You chose a case sensitive collation when installing SQL Server

You will have "CS" in this result:


You either live with it or rebuild the master database

  • Well since it's a commercial product, this is not my choice and I can't go and change the collaction. I try to understand where this behaviour comes from and especially why some login's seem to be different from others.
    – nojetlag
    Aug 24, 2011 at 6:46

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.