Fatal error: Uncaught Error: Class "GuzzleHttp\Promise\Tests\Thennable" not found in D:\xampp\htdocs\SSWPOS\vendor\guzzlehttp\promises\tests\NotPromiseInstance.php:10 Stack trace: #0 {main} thrown in D:\xampp\htdocs\SSWPOS\vendor\guzzlehttp\promises\tests\NotPromiseInstance.php on line 10