After creating a minimal test case (basically creating a Converter instance and calling convert method):
C# throws errors such as “GroupDocs.Conversion.Exceptions.GroupDocsConversionException: Object reference not set to an instance of an object”
Java throws errors such as “java.lang.IllegalArgumentException: Cannot insert a node of this type at this location.”
How to diagnose further this internal groupdocs problem?
What’s weird: your online test formular was able to convert some of our files properly. Is there a difference between your online test service and the provided SDKs (20.6 for java and 20.8 for c#)?