Getting 400 error

[rjsnh1522]

Hi I am using this in my old yii framework yii 1.0
and getting 400 error
Client error response
[status code] 400
[reason phrase] Bad Request
[url] https://api-3t.sandbox.paypal.com/nvp

I am not able to understand why . I have searched in stackoverflow also but haven't found any answer.

C:\xampp\htdocs\yii\app\protected\vendors\payum\core\Payum\Core\Exception\Http\HttpException.php(74)

62         } elseif ($response->isServerError()) {
63             $label = 'Server error response';
64         } else {
65             $label = 'Unsuccessful response';
66         }
67 
68         $message = implode(PHP_EOL, array(
69             $label,
70             '[status code] '.$response->getStatusCode(),
71             '[reason phrase] '.$response->getReasonPhrase(),
72             '[url] '.$request->getUrl(),
73         ));
74         $e = new static($message, $response->getStatusCode());
75         $e->setResponse($response);
76         $e->setRequest($request);
77         
78 
79         return $e;
80     }
81 }