Error- "System.Runtime.InteropServices.COMException: 'This method or property is not available because a document window is not active.'"

Question

I Installed WordToPDf in Visual Studio 2022 for my Project. But sometimes I open a file, this error occurs so I want to fix it. Can I get a solution or may need to change my WordToPDf Library ? Share your knowledges. Thank.

I changed my location used in Conversion method but It doesn't works.