Symptoms
Assume that you are using Microsoft SQL Server 2016 and 2017. When you run the sp_set_session_context stored procedure repeatedly (for example, more than 10 times) to set the KEY value parameter with a NULL value, you may receive an error message that resembles the following:
Msg 15665, Level 16, State 1, Procedure sp_set_session_context, Line LineNumber [Batch Start Line LineNumber ]
The value was not set for key 'KeyName' because the total size of keys and values in the session context would exceed the 1 MB limit.Resolution
This issue is fixed in the following 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 2017 Latest cumulative update for SQL Server 2016
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 terminologythat Microsoft uses to describe software updates.