Is it possible to find out who change the restrict access in SQL Log?

Copper Contributor

Hello all,


we have newly installed a SQL 2022 Server with database version 16.0.4055.4.


Somehow the restrict access will be automatically changed from MULTI_USER to SINGLE_USER. And therefore it caused a service crash. 


It happened until now three time periodically but on the server I cant find out which service or task did this job.


I tried to find out information unter C:\Program Files\Microsoft SQL Server\MSSQL16.SQLEXPRESS\MSSQL\Log

The only relevant records I could find are:

  •  2023-07-18 05:33:14.47 Server The maximum number of dedicated administrator connections for this instance is '1'
  • 2023-07-18 05:33:14.51 spid19s SQL Server started in single-user mode. This an informational message only.
  • 2023-07-18 05:33:15.14 Logon Login failed for user 'XXXX'. Reason: Server is in single user mode. Only one administrator can connect at this time. [CLIENT: <local machine>]


But I cant comprehend who did this change. Can someone give me an idea? 


Thank you.

4 Replies
SQL Server started in single-user mode.

@shenhsu , by default SQL Server start in multi-user mode. Only an admin change change stettings, so the anser is: It was an admin.



Hello Olaf, 


thank you for your reply. 

I found out that the Database was changed automatically in to single_user modus directly after the installation of DB patches. 


So it is like after installation of a new patch, every service got shutted down and the SQL Server restart in a single user modus with the message "SQL Server wurde im Einzelbenutzermodus gestartet. Diese Meldung dient nur zu Informationszwecken. Es ist keine Benutzeraktion erforderlich. (SQL Server started in single user mode. This message is for informational purposes only. No user action is required.)"

When installing SQL patches, SQL Server may start in SINGLE user mode to apply patches, but it should not remain in SINGLE user mode after the patches are fully applied.



Thank you for the information. I noticed sometimes it remains but sometimes not.

But the main thing is that I know where the problem is. 

Thank you :)