(Abbyy)Process Document Activity throws error as object reference

I am getting an error while processing invoice using process document activity whenever I debug and check it picks the right pdf and the right fcdot file in spite of this it almost takes 7 to 8 minutes to process during debugging and throws an error in the next step
as - System.NullReferenceException: Object reference not set to an instance of an object.
I have even initialized all the variables to avoid this error. but still, I couldn’t find a solution

If anyone could help…