Error 500 with send method

[TebanS2]

I have error 500 with 'send' method, everything else works fine for me

The error is :

Fatal error: Uncaught PocketException: Error could not parse response: in
/***/public_html/Pocket.php:205

Body :
{"actions":{"action":"tags_add","item_id":"3543162546","tags":"test"},"consumer_key":"","access_token":""}

Help me pls :(
I don't understand what is wrong