Early this morning Windows Updates updated one of our SQL 2019 servers with “SQL Server 2019 RTM Cumulative Update (CU) 4 KB4548597”.

That update resulted in the server being placed into a state whereby the SQL Server Service could not start. 

Event Viewer for System Showed every attempt at Starting the SQL Server service with the following error:

Event ID: 7024 “The SQL Server (MSSQLSERVER) service terminated with the following service-specific error:
WARNING: You have until SQL Server (MSSQLSERVER) to logoff. If you have not logged off at this time, your session will be disconnected, and any open files or devices you have open may lose data.”

Opening Windows Update, you could see that the update had been installed and that a server restart was required.

Restarting the server solved the issue and services came back up on their own.

Additional Information:
Windows Server 2016 Datacenter
The following Windows Updates were all installed at the same time:

Screen Capture of Windows Update History

2020-05 Cumulative Update for Windows Server 2016 for x64-based Systems (KB4556813)
SQL Server 2019 RTM Cumulative Update (CU) 4 KB4548597
Windows Malicious Software Removal Tool x64 – v5.82 (KB890830)
2020-04 Servicing Stack Update for Windows Server 2016 for x64-based Systems (KB4550994)

At this point I do not know if this issue is specific to this particular combination of KBs and Server 2016 or if other operating systems combinations will be affected. Will post updates if more systems are affected.