Symptoms
Assume that you perform a transaction log backup on the Availability Replicas for an AlwaysOn availability group in SQL Server 2012 or 2014. If the backup fails on the secondary replica, a backup lock is held on the primary replica. Therefore, subsequent transaction log backups are also unsuccessful.
Resolution
Update information
This issue is fixed in the following cumulative updates of SQL Server:
Cumulative Update 1 for SQL Server 2014 SP2
Cumulative Update 4 for SQL Server 2012 Service Pack 3
Cumulative Update 8 for SQL Server 2014 SP1
Recommendation: Install the latest 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:
Latest cumulative update for SQL Server 2012 SP3
Latest cumulative update for SQL Server 2014 (SP1/SP2)
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 terminology that Microsoft uses to describe software updates.