OVF Validation Fail

I am attempting to deploy a vApp for a customer into their catalog and getting a bit of an odd error.

Has anyone seen this one before?

Operation: Processed descriptor of Virtual Application Template.

Error: Validation failed for the OVF file you provided: Invalid argument '', should be empty.
Invalid argument '', should be empty.
Invalid argument '', should be empty.
Invalid argument '', should be empty.
Invalid argument '', should be empty..

Thanks in advance.