Getting error message

Hi, Recently we got the following 2 errors intermittently when creating the package using the same form, do you know what did happen? From the error message, it seems it complains about the pdf document has error, but we are using the same document for test case, and most of time are successful, only failed 1 or 2 times. error.validation.verifyDocument.couldNotBeFlattened error.eslx.inputValidation.documentPreverifyError Thanks, Cindy