Braintree makes regular updates to our server SDKs which follow semantic versioning guidelines. This page will guide you through the largest breaking changes that are specific to the language you are integrating with Braintree. Check the SDK's CHANGELOG for more information on changes.
Previous versions of the Braintree SDK supported class aliases with underscores, for instance
Braintree_Gateway to support the PHP standard PSR-0. Version 5.x.x and onward drop support for that standard because it is deprecated, in favor of PSR-4. This may require an update if you were previously using the underscore syntax to load Braintree modules.
If you were using underscores to load modules:
$gateway = new Braintree_Gateway([ 'environment' => 'sandbox', 'merchantId' => 'your_merchant_id', 'publicKey' => 'your_public_key', 'privateKey' => 'your_private_key' ]);
You should replace those with backslashes:
$gateway = new Braintree\Gateway([ 'environment' => 'sandbox', 'merchantId' => 'your_merchant_id', 'publicKey' => 'your_public_key', 'privateKey' => 'your_private_key' ]);
If you were using the now unsupported class aliases, you might see errors like the following:
PHP Fatal error: Uncaught Error: Class 'Braintree_Gateway' not found in /your/directory/YourFile.php