Function and usage of rest_application_password_check_errors() in wordpress


Answers ( 1 )


    The rest_application_password_check_errors() function in WordPress is designed to check for errors specifically when using application password-based authentication. This function plays a critical role in the REST API authentication process, ensuring secure and proper authentication using application passwords.

    Function Definition:

    rest_application_password_check_errors( WP_Error|null|true $result ): WP_Error|null|true


    • $result (WP_Error | null | true) - This parameter is essential as it represents the error status from another authentication handler. Its possible values are:
      • WP_Error: Indicates an existing error from a previous authentication handler.
      • null: Suggests that this function should handle the authentication check.
      • true: Implies that there is no error, or it's not for this handler to manage.


    • Error Checking: The primary purpose of this function is to check for errors during the authentication process when application passwords are used.
    • Workflow: It acts in a chain of authentication handlers, each having the opportunity to handle authentication or pass it down the line.

    Return Values:

    • The function returns different types of values based on the authentication status:
      • WP_Error: Returned if the application password used for authentication is invalid. This is a critical return type as it indicates a problem that needs resolution.
      • null: Returned if the function decides not to handle the authentication, passing the responsibility to the next handler in the chain.
      • true: Indicates that everything is in order with the authentication process, either because this function successfully authenticated the user or because there was no need for it to intervene.

    Usage Example:

    Imagine a scenario where you're implementing a custom authentication handler in your WordPress site, and you want to incorporate application password authentication. Here's how you might use rest_application_password_check_errors:

    function my_custom_authentication_handler( $result ) {
        // Your custom authentication logic here
        // Check for application password errors
        $result = rest_application_password_check_errors( $result );
        if ( is_wp_error( $result ) ) {
            // Handle the error, e.g., logging or modifying the error message
        return $result;
    // Hook into the authentication process
    add_filter( 'determine_current_user', 'my_custom_authentication_handler', 20 );

    In this example, my_custom_authentication_handler is a custom function hooked into the WordPress authentication process. It calls rest_application_password_check_errors to ensure that any application password-based authentication is correctly handled and any errors are appropriately addressed.

Leave an answer