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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.

share|improve this question
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. – StanleyJohns Aug 23 '11 at 1:10
up vote 4 down vote accepted

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

share|improve this answer
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 '11 at 6:46

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