Assume that you have a user hierarchy with Relational Online Analytical Processing (ROLAP) partition in Microsoft SQL Server 2008 R2 Analysis Services (SSAS 2008 R2), SQL Server 2012 Analysis Services (SSAS 2012), or SQL Server 2014 Analysis Services (SSAS 2014). You can create session cube successfully. When you execute Multidimensional Expressions (MDX) query on the created session cube that involves the grouping level(s) directly or indirectly, you may encounter the following issues:
The query fails, and you receive the following exception from the session cube:
Internal error: An unexpected error occurred (file 'mdpartitionrolap.cpp', line 948, function 'MDPartitionRolapMapper::AddRolapCondition').
The query returns null measure data, and there is no any exception.
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Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.