Database from Single_User Mode to Multiple_user mode (issues and solution)Posted: September 17, 2010
I don’t know why once in a while a user database can be switched to single_user mode. Sometimes it works fine with a Alter Database command: ALTER DATABASE [myDNName] SET MULTI_USER WITH NO_WAIT.
But you may have run into errors when you try to execute this command. You may need to wait for a while or run a KILL command to kill the currenct connection to the database we want to modify the setting.
Here is a link for how to proceed with the KILL: