Symptoms

When executing the PDF converter, the following error was witnessed

Message: Failed to convert HTML to PDF. ServiceName: PDFConverterService ServiceGuid: 99ae73bf-b5df-44dd-932e-615bb343585b InnerExceptionMessage: Message: Failed to convert URL to PDF. ServiceName: PDFConverterService ServiceGuid: 99ae73bf-b5df-44dd-932e-615bb343585b InnerExceptionMessage: Message: Could not get image from url. Could not get image from url. The URL is not accessible. Status code 0x191.The requested resource requires user authentication. ServiceName: PDFConverterService ServiceGuid: 99ae73bf-b5df-44dd-932e-615bb343585b InnerExceptionMessage
 

Diagnoses

This was a SharePoint integrated workflow that was utilizing the PDF Converter service. In this scenario the K2 server version did not match the version of the WFE.
 

Resolution

Upgrade the WFE to match the K2 for SharePoint version of the host server.