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XLANGs Object Reference Error when dynamically loading a map in BizTalk

This was one of those very frustrating errors that had a very simple solution.  I had an orchestration that was dynamically loading a map using a Fully Qualified Name (FQN) that is stored in BRE.  The exception looked like this:

{ORCHESTRATION_NAME} encountered an error: Object reference not set to an instance of an object.
at Microsoft.XLANGs.Core.Service.ApplyTransform(Type mapRef, Object[] outParams, Object[] inParams)
at {ORCHESTRATION_NAME}.segment3(StopConditions stopOn)
at Microsoft.XLANGs.Core.SegmentScheduler.RunASegment(Segment s, StopConditions stopCond, Exception& exp)

 Many times, this is the result of not deploying your DLL to the GAC, or not having a schema available in the Management Database.  I double checked both of those, and they were there.  I removed them and manually reinstalled them using gacutil, still got the same error.  It finally occurred to me to use reflection on the assembly to see if the FQN was wrong, and that was indeed my culprit.  The class name had .Outbound appended to it, and my orchestration was trying to load a class that ended in .Maps.  I could have changed the FQL in the BRE, but that would have been inconsistent with naming conventions elsewhere in the project.

The source of the error was adding the map to a Solution subfolder in Visual Studio:


This made the Namespace of the map default to Maps.Outbound:


Changing the highlighted property to .Maps and rebuilding/deploying fixed the issue.

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