Load order of plugins

The order in which plugins load is dependent on the method that is used to activate each plugin. The WordPress load order hook that is used to activate a plugin determines which point within the load process that plugin will load.

1. On the muplugins_loaded hook: Plugins that are activated via wpcom_vip_load_plugin( 'plugin-name' ) from client-mu-plugins. This method of code-activating plugins is recommended.
2. Before the after_setup_theme hook: Plugins that are activated via wpcom_vip_load_plugin( 'plugin-name' ) in a theme’s functions.php. This method is supported, but code activation from client-mu-plugins is preferred.
3. Before the plugins_loaded hook: Plugins that are manually activated from the WordPress Admin dashboard Plugins screen. This method is supported, but activating plugins through code is recommended.

Sometimes plugins have dependencies on running before specific hooks. To hook on very early actions or filters, load the plugin’s code from the /client-mu-plugins directory.