WordPress at a glance
action is not described

mu_plugin_loaded action-hook . WP 5.1.0

Fires once a single must-use plugin has loaded.

Usage

add_action( 'mu_plugin_loaded', 'action_function_name_4280' );
function action_function_name_4280( $mu_plugin ){
	// action...
}
$mu_plugin(string)
Full path to the plugin's main file.

Changelog

Since 5.1.0 Introduced.

Where the hook is called

In file: /wp-settings.php
mu_plugin_loaded
wp-settings.php 302
do_action( 'mu_plugin_loaded', $mu_plugin );

Where the hook is used (in WP core)

Usage not found!