Hi , 

We are using "SimpleViewer" component to view PDF file which was working normally on development server , after publishing on production , the pdf file was not showing with showing message "File Not Found" and after investigating the issue we found that session variable "SessionToken" used by the component and is always empty in "simpleviewer serve" although it was saved in database after calling "SimpleViewer_TokenizeFile" function that assign the token value in the sessionToken variable .