PDF to DOCX conversion error. 400 BAD Request.

Hi, 

I received this error com.adobe.pdfservices.operation.exception.ServiceApiException: description ='Bad Request.'; requestTrackingId='1b87ba50-30cb-4132-8eba-984f6cec55d0'; statusCode=400; errorCode=BAD_REQUEST  on one of the PDFs that I had uploaded for docx conversion. Could you please help me understand why this could have happened based on the request tracking id? The same doc when it was tried a few hours later, just worked fine, so it appears as though it was a service issue at that point in time, but why would I receive BAD REQUEST for a service issue/outage?

-Jay