Error 18456 is very common error in SQL Server. It generally occurs when there is some problem with the installation of MS Share Point Services. This error occurs in below mentioned scenario:
You have installed MS Windows SharePoint Services and you configured your SharePoint Services settings in SharePoint Central administration. After this, you specify the configuration database settings on Set Configuration Database Server page and then clicked 'OK'. After performing all these tasks when you clicked 'OK' you got the following error messages -
"Login failed for user 'DOMAINNAMEACCOUNTNAME'. (Error code: 18456)
Login failed for user 'NT AUTHORITYNETWORK SERVICE'. (Error code: 18456) "
If the account using for this purpose doesn't have the database creation rights in the MS SQL Server these types of errors occur. This issue generally occurs when the account is not the member of the Security Administrator role.
To solve this issue you need to add an account to the Database Creators role and to the Security Administrators role in SQL server which will certainly resolve the issue. To perform this task, just follow the below steps:
- Add an account to the Security Administrator role that the application pool is running.
- On Configuration Administrative Virtual Server page of SharePoint Central Administration create a new application pool and click 'OK'.
- Restart IIS i.e. Internet Information Services of Microsoft, click 'Run' and type ' iisreset ' in the open box and click 'OK'
- Now, on the Application Pool changes page click 'OK' and set the configuration database server page of SharePoint Central Administration after specifying the configuration database settings.
After doing all the above setting if you still get the same error then you will not be able to access the database file of MS SQL Server. In this case you have to repair the file with some third party SQL Database Repair software.