Our company has just been bought and the over the weekend I have brought up the last few machines to plug into their network (they are under a different Windows Domain).

The last machine is our Vault system and the SQL Server was using Windows Authentication.

I have plugged it into their network and its working fine, but i cannot connect to SQL Server with Management Studio and, I fear, no backup jobs will also be working.

When I try to login under Windows Auth, it has the user name of "NEWDOMAIN\Administrator" (greyed out) and then presents a "login failed" message with error code "18456".

Can anyone help me with this, or will I just have to reinstall SQL Server, Vault and restore the backup I took before the move?


You need to give us the actual error message. 18456 is just an umbrella error that cover several different login errors. The error message would had been traced into ERRORLOG file and the system NT event log (eventvwr.exe).

  • Is the SQL Server host machine in the NEWDOMAIN now, or is it in the OLDDOMAIN?
  • Is there any trust relationship between the NEWDOMAIN and the OLDDOMAIN?
  • Is the domain controller of the OLDDOMAIN available in the new location?
  • Why do you even expect NEWDOMAIN\Anyuser to be able to log in into SQL? Did you add them as valid logins? You need to log in with an old valid account first and add the NEWDOMAIN\SomeUser and NEWDOMAIN\PtherUSer as valid logins before attempting to use a new domain.

In the likely event that you locked yourself out of SQL Server, follow the steps in Troubleshooting: Connecting to SQL Server When System Administrators Are Locked Out

  • * The machine is in the new domain now, 300 miles away from the old office and domain) * Their is no knowledge between the two domains, we have sold the company to someone completely different * The OLDDOMAIN pdc is not available in old location * Its one thing I didnt think about, thinking about many machines and backing up and transportation in a time frame of 1 day took its toll I am not sure what I could have done any differently ... I am not a SQL Server guru. But thats neither here no there, I was hoping there might be a solution other than reinstall everything. Thanks anyway
    – Dan
    Apr 26 '10 at 19:15
  • The links shows how you can add the admins of the new domain to the SQL Server syadmin group, thus granting them access to the server. From there you can build all needed security requirements. It won't be trivial, but you won't need a full re-install. Apr 26 '10 at 20:57
  • Thanks the link did work (eventually) my colleague had tried it and failed, but he omitted the semicolon in the "-m" startup parameter. We then got in and added the new "NEWDOMAIN\Administrator" login and all was great. Thanks sooo much!
    – Dan
    Apr 27 '10 at 15:44

Windows authentication will automatically use your current user account to log on to SQL Server, so if you're logged on using NEWDOMAIN\Administrator, this is what will be sent to SQL Server (and it will not accept it, if that was not defined as a valid login).

You need to either log on using OLDDOMAIN\SomeValidUser and then use Windows authentication, or use SQL Server authentication (if it is enabled on the server); then you will need to grant proper permissions to users in the new domain, and then you will be able to use Windows authentication again.

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