Are you landing on this page because you are searching for more information about Producer ? Stumped
I can not use a PPTX where as DOCX works fine.
For PPTX, I get the following error.
Unknown relationship type: http://schemas.openxmlformats.org/officeDocument/2006/relationship/slide Parameter name: relatiuonshipType
We're goign to need a lot more information to begin troubleshooting a problem like this. Have you visited OpenXMLDeveloper.org?
What type of solution? What are you building? are you editing existing documents or creating new ones?
Note that there is a typo in "relationship" in the text above: "Parameter name: relatiuonshipType"