Hi @arash ,
Welcome to the community forums!
Thanks for letting us know about this issue.
Could I ask you to perhaps elaborate on the issue a bit more?
It might help us find out what's causing the issue faster. 🙂
When do you receive the JSON code?
Is it when you click on "Continue to PayPal"?
Or is it after you pay with PayPal, when you get redirected back into the site?