Under following situation, internal thread deadlock may occur on primary or secondary replica of availability group in Microsoft SQL 2016 Service Pack 2 (SP2) and 2017 leading to log writer thread in a stuck state.
When you are adding multiple databases to AG using auto seeding and heavy write transactions are occurring on primary replica.
AG configuration is updated while there are heavy write transactions on primary replica.
When this issue occurs no changes from AG perspective gets flushed.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
This issue is fixed in the following cumulative updates 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:
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