“Unable to read the WordPress site on that URL” error message.
Ensure that you’ve typed in the URL correctly. This should be the root site address (no /wp-admin or other login link. Something like http://yourgroovydomain.com)
If it’s correct, visit your site’s dashboard in a web browser, and make sure WordPress is updated on your site. (If your site uses WordPress 4.0 or lower, you will need to update your WordPress installation to use the app.)
Verify that XML-RPC is functioning properly. (XML-RPC is the service the app uses to communicate with your site.) You can use our XML-RPC troubleshooter: http://xmlrpc.eritreo.it/
Go to the W3C Markup Validator and type in the URL of your WordPress site. If you get a response such as “… one or more bytes that I cannot interpret as UTF-8″ that is most likely what is causing the app to have trouble with your site.
Try with the default theme and with no active plugins.
(Trying it with the default theme and plugins disabled will help pin down where the problem is. If everything works that way, you can go back and enable your theme and then try it again. If everything still works then you go back and activate each plugin one at a time until you find the one that is causing the breakage.
Turn on the ‘debug mode’, that enables extended log format, and check the log file. The debug mode is available in the Me section (profile icon) -> Help & Support and select Extra Debug.