Msg 15150 – Cannot Alter The User ‘dbo’.

Question

Getting this error message - "Msg 15150 – Cannot Alter The User ‘dbo’." When using SSMS -> Login Properties -> User Mapping to change/modify the schema owner from 'dbo' to another user.

Instead of using this approach, I went with T-SQL using this command:-

=================================================================

use [dbname]

exec sp_changedbowner 'new-dbuser'

go

Commands completed successfully. Completion time: 2025-04-08T08:19:57.3508306-04:00

==================================================================

I get the confirmation above. However, when I checked the Using SSMS -> Login Properties -> User Mapping, it is still showing 'dbo'. Thus, this SP_CHANGEDBOWNER is NOT does what is supposed to do.

Is there a workaround?

Your input is greatly appreciated - THANK YOU!

Answer 1

Hi Vince Husenajr
It seems like you're encountering a common issue when trying to change the schema owner from 'dbo' to another user in SQL Server. The error message "Msg 15150 – Cannot Alter The User ‘dbo’" indicates that the operation you're attempting is not allowed directly through the SSMS interface.
To resolve this issue, you can follow these steps:
Change the Database Owner to 'sa':

• One effective workaround is to change the database owner to 'sa' (the system administrator account). This can be done using the following T-SQL command:

    USE [dbname]
    EXEC sp_changedbowner 'sa'
    GO
  

• This command changes the database owner to 'sa', which should allow you to modify the user mappings as needed Verify the Change:
  • After executing the command, verify that the database owner has been changed by checking the properties of the database in SSMS.
    Reassign Ownership:
    • If you need to assign the ownership to a different user, you can now do so without encountering the error. Use the following command to change the owner to your desired user:

    USE [dbname]
    EXEC sp_changedbowner 'new-dbuser'
    GO
  

  SQL SERVER – FIX: Msg 15150 – Cannot Alter The User ‘dbo’:
  • This blog post provides a detailed explanation of the error and suggests changing the default owner to 'sa' as a solution
  I would request you to refer the below mentioned links for more information
  https://blog.sqlauthority.com/2017/12/12/sql-server-fix-msg-15150-cannot-alter-user-dbo/