Error: 32 occurring when converting .vmx to .ova file

I am converting a .vmx for to a .ova file using the ovftool. I have used the ovftool to do this operation in the past,  and would occasionally see the error:

Error: 32
Completed with errors

Whenever this error occurs, the conversion operation fails, and the resultant .ova file is created as an empty file. (Size=0)
I am now seeing this error more consistently and need to determine why it is occurring. 

I am using version 4.3.0 build 12320924.

Any ideas or suggestions on how to avoid this error, or what it means would be very helpful. 

Thanks!

Bill