Sandbox - Always get 'System Error' when trying to do a payment

[kelumch]

I'm using Paypal with my Android mobile application. I have been using the sandbox system for more than an year. Since the last week, I'm always getting below error from Paypal system.

{"name":"INTERNAL_SERVICE_ERROR","message":"An internal service error occurred.","information_link":"https://developer.paypal.com/docs/api/payments/#errors","debug_id":"46f7494320448"}

I have no clue to get through this problem. Any help is greatly appreciated.