Symptoms
Assume that you are trying to upgrade a SQL Server 2016 mirrored instance to SQL Server 2017 by performing a rolling upgrade. After you complete upgrading, you may notice that the mirroring session is not able to synchronize. This may prevent you from completing the rolling upgrade. Additionally, an error message that resembles the following is logged in the SQL Server error log.
Error: 1479, Severity: 16, State: 1.
The mirroring connection to "<server network address>" has timed out for database "<database name>" after 60 seconds without a response. Check the service and network connections.
Resolution
This issue is fixed in the following cumulative update for SQL Server:
Each new cumulative update for SQL Server contains all the hotfixes and all the security fixes that were included with the previous cumulative update. Check out the latest cumulative updates for SQL Server:
More Information
To get more information about how to upgrade mirrored instances, you can refer to the following link:
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
References
Learn about the terminologythat Microsoft uses to describe software updates.
