Resolved issue

In v0.1, there’s a file called:
tagUserNotifcation.php

On line 88, it’s calling the option “notifyOnUserTag_emailTemplate” which does not exist by default, nor does the plugin add the option.

So on line 92, I delete the first part “if($template )” so it’s shows this instead:
$template = file_get_contents(dirname(__FILE__) . ‘/defaultTemplate.php’);

After making that change, the plugin now works in WP 3.9.1

https://www.ads-software.com/plugins/tag-user-notification/