We use the XML-RPC WordPress API in some applications. On this particular blog we get this error in the image below. We’ve tried removing plugins, re-installing the blog, and contacting the hosting, but we can’t figure-out what’s wrong and how it is disabling the access.
I am not familiar with WordPress and the plugins architecture so I do not know if this is in the code or in the database (credentials in image are fake).
As my point of view, this problem can be for 3 reasons:
1) Your server hasn’t xmlrpc extensions installed or enabled.
2) WordPress blocks every xmlrpc calls (check security plugins if you have any installed and .htaccess)
3) Your server deny your xmlrpc calls because it believes that you are doing an attack (tipycally DOS attacks). Check that your server hasn’t blocked your ip.