Asp.net webForms problem : Generate an empty pdf on production Server!

Question

In my webForm project as follow :

1. I have a button which user click on it
2. call a web method (via jquery request) to extract some binary data from sql server as pdf
3. Then give a user to download/view the pdf via browser.

This works for my development machine. However, this fails on production server and give to user an empty pdf!

Where is my problem & how to solve it?

Here is jquery request to my web method :

Answer 1

Thanks for reply.
I don't get null value. but the binary data which returns from sql server is an empty pdf!
please see this link which contains my code :

https://stackoverflow.com/questions/68642520/asp-net-webforms-problem-generate-an-empty-pdf-on-production-server