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I have changed the AD domain on a SQL Server 2008 box which was setup only for Windows Authentication. Now the domain has changed, I can't log into the SQL Server instance even as the domain's Administrator account.

Is there a way of updating the server security settings without logging into the SQL instance first through a command switch / registry setting / etc..

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How about logging in as SA and making the changes? – joeqwerty Apr 27 '10 at 19:11
Windows Authentication Only. There may not be an SA account enabled. – Sean Howat Apr 27 '10 at 19:16
Windows Auth only, so no SQL login will work, tried logging in as local server Administrator account too - that's not got permissions setup either. – Ollie Apr 27 '10 at 19:18
up vote 0 down vote accepted

I would try to start your SQL Instance in single user mode. You'll need to stop the service first and then start it up again with the -m option. This should allow anyone from the sysadmin server role to login to the instance (but only one at a time). The command to start it up would look like this:

"%Path to SQL server%\MSSQL10.MSSQLSERVER\MSSQL\Binn\sqlserver.exe" -sMSSQLSERVER -m

Once it's started in single user mode try logging in with a sysadmin account and adding an account to SQL Server. Then start it back up again in regular mode and try to log in with the user you've added.

I found a link regarding this topic that I think might help. It mentions using single-user mode as well but seems to be tailored to a situation where your admins are locked out. Check it out here.

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