What is SSAS error "An unexpected exception occurred" or 0xC1000016

When working with SQL Server Analysis Services, it is not uncommon to see this error message "An unexpected exception occurred". This is the most misunderstood message in SSAS. If you try to search this particular error message, you can get quite a lot of hits in the search engine. An Internet results can come back with some Microsoft KB articles, Connect feedback posts, and Forum posts.

The SSAS error log msmdsrv.log in the Log folder may also contains an error code 0xC1000016. The message may look like the following

Message: (Source: \?R:OLAPLogmsmdsrv.log, Type: 3, Category: 256, Event ID: 0xC1000016)

This "An unexpected exception occurred" error (or error code 0xC1000016) really means some exception happens, and the natural of the exception is unknown. Because it is an unknown exception, the exception can be any cause. If you try to follow the KB articles or forum discussion posts, you can get lost easily. You are likely directed to some articles that does not necessary match the root cause of your particular exception, and you may waste time and effort trying to following the solutions on these articles.  

This "An unexpected exception occurred" error can Sometimes crash the Analysis Services process, but a crash does not always happen.

 In order to troubleshoot this error, you need to first locate the mini exception dump file generated when this error occurs. When Analysis Services encounters this error, it always creates a .mdmp file in the Log folder for post-mortem analysis. To find out the location of the Log folder, just connects to Analysis Services using SQL Server Management Studio. In the Object Explorer, right click on the Analysis Services instance, choose Properties. A list of SSAS server properties and their values shows up. The LogDir server property value is the location of the Log folder.

After you find the mini crash dump files, you can open a Microsoft support case to analyze the cause of the crash. A Microsoft support engineer can open the crash dump to look at the call stack of the offending thread. Unfortunately there is no public database you can match the call stack of a crash dump with an existing bug. The public KB article of a SQL Server hotfix does not contain the call stack information. A Microsoft support professional has the necessary tools to confirm if the crash matches a known bug or fix.  

There is a chance the exception you encounter is a bug that has been fixed, especially if you are not running the latest cumulative update of SQL Server. You can first try install the latest Cumulative Update (CU) of the SQL Server installation, see if the problem still occurs.

The Microsoft SQL Server Version List at http://sqlserverbuilds.blogspot.com/ is the best place to find the latest SQL Server updates.

An unexpected exception in SSAS is always a product bug. Customer should engage Microsoft to report the problem and get a fix if there is no workaround and there is no fix yet. Follow this link to contact Microsoft Support http://support.microsoft.com/common/international.aspx?RDPATH=%2fselect%2fDefault.aspx%3ftarget%3dassistance