Edit file File name : bt-sandbox.php Content :<?php require_once('braintree/final/braintree/lib/Braintree.php'); /* //braintree production Braintree_Configuration::environment('production'); Braintree_Configuration::merchantId('85f4dtcxzp6p924q'); Braintree_Configuration::publicKey('3hw5mfz536gzn4jc'); Braintree_Configuration::privateKey('47f67be7bf627608c012b98a0b8b30d1'); */ // braintree sandbox Braintree_Configuration::environment('sandbox'); Braintree_Configuration::merchantId('d68m73wzrttmy8t9'); Braintree_Configuration::publicKey('h7c2bm97b72bm9fd'); Braintree_Configuration::privateKey('67cf79121710d11dfe308c95c8bb3987'); Save