XML-RPC Error (404): Unknown error

I am using Moodle 2.3.3 and Joomla 2.5.9 with the Joomdle plugin 0.9.

Every time someone registers a new account on the Joomla site they are met by the XML-RPC Error (404): Unknown error web page when they click the register button.

Any ideas on what is wrong or how to fix this?

I too have the same problme following the update of Moodle 2.4.1 + and Joomla 2.5.9 with the plugin Joomdle 0.9. Every time someone registers a new account on Joomla met by the XML-RPC Error (404): Unknown error page when you click the register button.

404 usually means either:
- some misconfiguration in Moodle side
- or badly configured module in page that gives error

It also can be caused by other things, so it can be tricky to track.