Code/Plugin nach Joomla-Update ausführen, nach com_joomlaupdate 

public function onAfterInitialise()
{
    $component = $this->app->input->getCmd('option', '');
    $view = $this->app->input->getCmd('view', '');
    $layout = $this->app->input->getCmd('layout', '');
    if (($component === 'com_joomlaupdate') && ($view === 'default') && ($layout === 'complete')
    {
        // Your code here
    }
}

 https://forum.joomla.de/thread/6140-plugin-ausf%C3%BChren-nach-joomla-update/?postID=42206#post42206