Not able to open the word Doc with Docx extention

I created a word Document using aspose word utility.
When I use the following statement, word document opens fine:-

_doc.Save("FileName.doc", SaveFormat.Doc,SaveType.OpenInWord, Response);

But, when I use the following statement, I get the attached error:-

_doc.Save("FileName.docx", SaveFormat.Docx,SaveType.OpenInWord, Response);

saw another similar post and included

Response.End();

It fixed the problem.

Thanks
Saurabh.

Hi
It is nice that you already found solution independently.
Best regards.