Fix: The Document Can’t Be Opened Because it is not a Supported Visio Diagram
If you recently created a Vision Service Application, you still may only be able to view VSDX, VSDM, or VDW files as Visio Web parts. You will receive the following error
Error: The document can’t be opened because it is not a supported Vision diagram.
Make sure that the “Web Drawing URL” web part setting is set to a valid VSDX, VSDM, or VDW file.
Convert the Visio file into a VSDX, VSDM, or VDW Visio format in order to open or view it.