CU18 patch failed on my sql server 2022. SQL server is not restarting (Database engine patch failed)

Question

How to fix this error, i got this error after applying cu18 patch to sql 2022, the error only cites that sql server agent coulnt start as sql server is down, the event viewer error code is 7001

Answer 1

When you install a CU or a GDR, Setup runs a script msdb110_upgrade.sql which does a lot of things, and of which some certainly are questionable. And if this script fails, you are in trouble.

This is where things go wrong:

2025-06-19 19:51:29.47 spid15s Error: 15138, Severity: 16, State: 1. 2025-06-19 19:51:29.47 spid15s The database principal owns a schema in the database, and cannot be dropped. 2025-06-19 19:51:29.47 spid15s The failed batch of t-sql statements :

-- Do not recreate the user for Managed instance (EngineEdition 8). -- Recreation of the existing login does not happen for MI, so we don't need to recreate the user. IF EXISTS (SELECT * from sys.database_principals where name = N'##MS_PolicyEventProcessingLogin##') AND SERVERPROPERTY('EngineEdition') <> 8 DROP USER [##MS_PolicyEventProcessingLogin##]

I see that this is on a virtual machine, so the best may be restore a backup of the VM, if there is one before the upgrade. When you have restored in run:

USE msdb
go
SELECT * FROM sys.schemas WHERE principal_id = user_id('##MS_PolicyEventProcessingLogin##')

Review the schema in question and drop it or make dbo the owner of it.

If you cannot restore the VM, you can add trace flag 902 as a startup parameter to SQL Server. This instructs SQL Server not to run the upgrade script. Once you have cleaned up the schema for ##MS_PolicyEventProcessingLogin##, remove the -T902 startup option again, and restart SQL Server. Hopefully, the upgrade script now completes successfully.