As we know WordPress community exist on wordpress.com & wordpress.org
WordPress.org is downloadable CMS (Content Management System) distribution for self hosted used by web designers & web developers.
Being CMS lead developer Automattic want’s it’s wordpress.com experience available to it’s wordpress.org users. So they developed plugin like JetPack for WordPress self hosted websites.
JetPack Error Description: Your website needs to be publicly accessible to use Jetpack: site_inaccessible
Error Details: The Jetpack server was unable to communicate with your site [HTTP 404]. Ask your web host if they allow connections from WordPress.com. If you need further assistance, contact Jetpack Support: http://jetpack.me/support/
As written in my earlier blog post about ‘How to disable WordPress Pingbacks & Trackbacks, One of the old Feature & Core Functionality of WordPress, Optimum Performance Tip’
This error related file called xmlrpc.php installed with wordpress. If you have blocked access to or accidentally deleted file called ‘xmlrpc.php’ at root of your WordPress installation this will caused the above error to occurred that ‘The Jetpack server was unable to communicate with your site [HTTP 404].’
Solution: So edit your code to allow access to ‘xmlrpc.php’ from WordPress.com or just delete or comment it out your code (Add hash # before all code lines to comment out) from .htaccess
#XML RPC Interface for weblog clients, Trackback & Pingback Protection <FilesMatch "^(xmlrpc\.php|wp-trackback\.php)"> Order Deny,Allow Deny from all Allow from wordpress.com </FilesMatch>
Hope it helps,
Thanks & Regards