Fatal error: Declaration of action_plugin_sidebar::register(&$controller) must be compatible with dokuwiki\Extension\ActionPlugin::register(Doku_Event_Handler $controller) in /var/www/html/wiki/lib/plugins/sidebar/action.php on line 28
dokuwiki\Exception\FatalException: Declaration of action_plugin_sidebar::register(&$controller) must be compatible with dokuwiki\Extension\ActionPlugin::register(Doku_Event_Handler $controller)

dokuwiki\Exception\FatalException: Declaration of action_plugin_sidebar::register(&$controller) must be compatible with dokuwiki\Extension\ActionPlugin::register(Doku_Event_Handler $controller)

An unforeseen error has occured. This is most likely a bug somewhere. It might be a problem in the sidebar plugin.

More info has been written to the DokuWiki error log.