You use the AlwaysOn Availability Groups feature in Microsoft SQL Server 2014 Service Pack 1 (SP1) or Microsoft SQL Server 2012 SP2. When a stalled dispatcher system dump occurs, an automatic failover might occur on the availability groups if the AlwaysOn Availability Groups feature is configured to do this. This failover is expected. If the availability group is configured for manual failover, the availability group will transition to the RESOLVING role, and the databases will be offline (that is, they will be inaccessible by your application) until the health issue is fixed. In either case, a service outage could result.
The health issue that may be detected is a lease time-out, and the SQL Server error log will display the following text some time after the stalled dispatcher is reported:
2014-05-30 10:30:50.19 Server Error: 19407, Severity: 16, State: 1.
2014-05-30 10:30:50.19 Server The lease between availability group 'TFSAG001' and the Windows Server Failover Cluster has expired. A connectivity issue occurred between the instance of SQL Server and the Windows Server Failover Cluster. To determine whether the availability group is failing over correctly, check the corresponding availability group resource in the Windows Server Failover Cluster.
Service pack information
To fix this issue, get Service Pack 3 for SQL Server 2012.
For more information about SQL Server 2012 Service Pack 3 (SP3), see bugs that are fixed in SQL Server 2012 Service Pack 3.
Cumulative update information
This problem was first fixed in the following cumulative update for SQL Server:
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Learn about the terminology Microsoft uses to describe software updates.