Symptoms
Assume that you create an Always On Availability Group (AG) with automatic seeding in Microsoft SQL Server 2016. When you try to change the SEEDING_MODE to MANUAL by using ALTER AVAILABILITY GROUP on the primary replica, then you notice that SQL Server does not cancel current seeding operations to the secondary replica.
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Resolution
This issue is fixed in the following cumulative update for SQL Server:
About cumulative updates 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 cancel automatic seeding, you can run the following command:
--Connected to primary replica
ALTER AVAILABILITY GROUP ag
MODIFY REPLICA ON 'node2'
WITH (SEEDING_MODE = MANUAL)
GO
To check whether the latest seeding operation was canceled or still running, you can run the following query against the DMV:
select current_state, failure_state_desc, * from sys.dm_hadr_automatic_seeding order by start_time desc
References
Learn about the terminology that Microsoft uses to describe software updates.