Updating Error Message

Good Morning,

I use your plugin on three different sites and all are having the same problem. The plugin is currently working but I’m stuck on version 5.2.1. Any time I try to update, I get the following message:

Method Not Implemented

GET to /fss/wp-admin/update.php not supported.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

Other plugins are updating correctly. Any ideas?

Thanks, Tyler

http://wordpress.org/plugins/mail-on-update/