Assume that you have a Multidimensional OLAP (MOLAP) dimension that has enabled the Proactive Caching feature in Microsoft SQL Server Analysis Service (SSAS) and the dimension is referenced by a cube that has a Relational OLAP (ROLAP) partition. When data changes in the source database cause proactive caching to be triggered for the dimension, a crash occurs, and you receive the following error message:
Internal error: An unexpected error occurred (file 'FileName', line LineNumber, function 'FunctionName').
The issue is fixed in the following cumulative updates for SQL Server:
To work around this issue, use Hybrid OLAP (HOLAP) mode instead of Relational OLAP (ROLAP) mode in SSAS 2012.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.