Yes the reason for CSS.runtime is got. There is a dll needed called CSSParser.dll that I’ve put.

But solution for error of opening PDF files is still cant be reached.

But my concerned person told me that there in an exe called w3wp for generating PDFs when multiple users tried to Generate PDFs at the same time this exe is conflicting and an error is thrown when opening PDFs.

So I want a solution so that I can avoid this conflict of exe when multiple users tried to generate PDFs at the same time.

So kindly let me know what should I do about that.