facing issue when I make payment with payapal sendbox

[Theappideas]

Hello,

here I am shearing the image what was the issue please help me.

paypal.sdk: Exception parsing server response
org.json.JSONException: End of input at character 0 of

paypal.sdk: request failed with server response:

paypal.sdk: INTERNAL_SERVER_ERROR

my client is : AQfgl17dkw3MQ-DaGVpp0nVbxggpHi_96TT7xZmtbqN-laNgsl0EpFmqirzZ14A8hvUfCQGGWdmVbpZB

Thank you, please guide me what was my mistake.