Fatal error: Uncaught Exception: Cannot find necessary environmental variables. See https://github.com/braintree/braintree_php_example#setup-instructions for instructions in /var/www/html/ohnishi-test.site/braintree_php_example-main/braintree_php_example-main/includes/braintree_init.php:11 Stack trace: #0 /var/www/html/ohnishi-test.site/braintree_php_example-main/braintree_php_example-main/public_html/index.php(1): require_once() #1 {main} thrown in /var/www/html/ohnishi-test.site/braintree_php_example-main/braintree_php_example-main/includes/braintree_init.php on line 11