Symptoms
Assume that you have a database that is in single-user mode in Microsoft SQL Server 2014 and 2016. You may notice that multiple deadlocks will occur simultaneously when many connections try to access the database. Because of this, the deadlocks keep occurring even after you exit all the connections.
Resolution
Service pack information for SQL Server
This update is fixed in the following service packs for SQL Server:
Service Pack 2 for SQL Server 2016
Service Pack 3 for SQL Server 2014
About service packs for SQL Server:
Service packs are cumulative. Each new service pack contains all the fixes that are in previous service packs, together with any new fixes. Our recommendation is to apply the latest service pack and the latest cumulative update for that service pack. You do not have to install a previous service pack before you install the latest service pack. Use Table 1 in the following article for finding more information about the latest service pack and latest cumulative update.
How to determine the version, edition and update level of SQL Server and its components
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.