Symptoms
When you process a table in a tabular model in Microsoft SQL Server 2016 Analysis Services (SSAS), you receive an error message that resembles the following:
The JSON DDL request failed with the following error: Failed to execute XMLA. Error returned: 'An unexpected error occurred (file 'tmmdmodeltm.cpp', LineNumber, function 'MDModelTM::CreateHierIterRequest').
Resolution
This fix is included in Cumulative Update 2 for SQL Server 2016 Service Pack 1.
Each new build for SQL Server 2016 contains all the hotfixes and security fixes that were included in the previous build. We recommend that you install the latest build 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 terminology Microsoft uses to describe software updates.