I am trying to port an old XNA project to MonoGame and I am getting the following error when I build my Content project in the Pipeline Tool:

"Error importing file: invalid Vector subscript".

This was for an older FBX file that I upgraded to FBX 2013 with the Autodesk FBX Converter app. In the Properties window for the FBX file, under Processor, I've tried both "Model - MonoGame" and a custom processor and I get the same error with either one:

What is the problem with the 3D model and how can I get around it?