SQL server error 15150

SQL server error 15150 occurs when while updating the login from dbo to some other login due to incorrect ownership of the database.

Here at Bobcares, we have seen several such SQL related issues as part of our Server Management Services for web hosts and online service providers.

Today we’ll take a look at the cause for this error and see how to fix it.

What is SQL server error 15150?

SQL Server Error 15150, also referred to as Error 15150 in SQL Server, occurs when SQL Server prevents changes to the dbo user because of database ownership or permission restrictions. It commonly appears while updating login mappings or modifying database users.

In some cases, administrators may also encounter the message “Cannot drop the user ‘dbo’. (Microsoft SQL Server, Error: 15150)” when attempting to modify or remove the dbo user. The error is often related to an incorrect database owner, especially after a database restore, migration, or ownership change. Verifying the current database owner before modifying user mappings helps avoid this issue.

Common Causes

Error 15150 SQL Server commonly occurs due to one or more of the following reasons:

• The login is the current database owner.
• The dbo user is being modified directly.
• The database ownership was not updated after a restore or migration.
• The login does not have sufficient permissions to change database ownership.

Procedure for updating the logins

Before changing the login mapping, verify the following:

• Ensure the user is not the current database owner.
• Remove unnecessary dbo role membership if applicable.
• Confirm the new login has the required database permissions.
• Back up the database before making ownership changes.

How to fix SQL error 15150?

To fix this issue, we need to change the default owner to ‘sa’ and then try to update the login.

Moreover, the ‘sa’ account of SQL Server has the special privileges necessary to manage the database. So, this ‘sa’ default account is administrative.

By default, this account is disabled to avoid unauthorized access to the database.

Use <database_name>
GO
sp_changedbowner ‘sa’
GO

OR

USE <database_name>
ALTER AUTHORIZATION ON <database_name>::DATABASE_NAME TO sa

Troubleshooting

Issue	Possible Cause	Solution
Cannot alter the dbo user	Database ownership conflict	Change the database owner before updating the login.
Ownership change fails	Insufficient permissions	Use an account with administrative privileges.
Login mapping still fails	Existing user mapping or cached session	Refresh the connection and retry the update.

[Need any further assistance in fixing SQL errors? – We’re available 24*7]

Conclusion

SQL Server Error 15150 is usually caused by database ownership or permission restrictions when modifying the dbo user or updating login mappings. Resolving Error 15150 in SQL Server by assigning the correct database owner and verifying permissions helps complete the login update successfully.