Upgrading

The CakePHP 5 branch uses current component/helper APIs. Follow installation and review composer.json before updating an older application.

Configuration and templates

The global Flash configuration now supplies defaults to both the component and helper. Existing explicit load options take precedence. Custom order and ajaxDetectors lists now replace their built-in lists instead of appending to them. Merge the restored config/app.example.php entry into your application configuration when you want shared defaults. TransientFlash holds messages at runtime and should not be copied into application configuration.

Keep parent::initialize() and the void return type when updating AppController and AppView. Provide all five application templates, including info.php.

Message behavior

Use a positive stack limit. A zero or negative limit now fails when the component or helper loads. All component message paths enforce the configured stack limit. Transient stacks retain exactly that number of messages. duplicate: false suppresses identical controller entries in either store.

On AJAX requests, direct set() and message() now follow noSessionOnAjax, just as typed calls do. Component transient calls accept Throwable and normalize it to message text and code. Plugin-specific elements preserve their message type, and direct calls now honor the plugin option. AJAX headers also work for actions returning a response directly.

Helper transient calls now retain supplied options. A configured helper key is used by a parameterless render(), and type filtering also recognizes ordinary CakePHP core flash entries.

CakePHP 6 support is not declared. These changes keep the CakePHP 5 code ready for a separate compatibility upgrade once its requirements are known.