Thread:Project:Support desk/if someone edit the mediawiki page me or who has the mediawiki account need to get email notification. how can i do that?/reply

What help page say that?

That means /opt/lampp/htdocs/mediawiki/extensions/NewUserNotif/NewUserNotif.php doesn't exist on your server. It's a MediaWiki extension (Extension:New User Email Notification). You need to download the extension and install it on your server.