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InvalidArgumentException: planId cannot be null in /var/www/html/PayPal-PHP-SDK/paypal/rest-api-sdk-php/lib/PayPal/Validation/ArgumentValidator.php:25 Stack trace: #0 /var/www/html/PayPal-PHP-SDK/paypal/rest-api-sdk-php/lib/PayPal/Api/Plan.php(331): PayPal\Validation\ArgumentValidator::validate() #1 /var/www/html/ws/paypal/updatePlan.php(15): PayPal\Api\Plan::get() #2 {main}