Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource opencart

Well this was very simple case but annoying, due to new restrictions on browser I guess , my site was redirecting to www via htaccess and I didnt made change in url in config file so url was without www so it was not sending any of json ajax request.
Just fix url of site to as per redirection and you are good to go. I hope it helps