Access violation when you query sys.dm_exec_requests during database recovery

Queries against sys.dm_exec_requests might raise an access violation and generate a dump file if they run while a database is still recovering. This issue can occur during a database RESTORE operation, during startup recovery, or before an availability group replica finishes coming online. The SQL Server error log contains entries that resemble the following text: This issue occurs because of a change that causes internal in-memory structures to be referenced before they're fully initialized. Microsoft is aware of this issue and is investigating a fix. Until a fix is available, use one of the following mitigations: Enable trace flag 4696 to opt out of the code change that causes this issue. If you enable this trace flag, monitoring queries that query sys.dm_exec_requests or sys.sysprocesses on secondary replicas might return error 976 or error 978, as they did before you installed this update; Avoid queries against sys.dm_exec_requests for databases that are recovering; Uninstall this update.

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