WordPress Speed Up Service | WordPress Website Maintenance Packages WordPress 4.9. Theme php file editing., by mussy Further to this thread, which is now closed: https://wordpress.org/support/topic/cant-edit-main-theme-php-files-after-upgrading-to-4-9/ Regarding error message: “Unable to communicate back with site to check for fatal errors, so the PHP change was reverted. You will need to upload your PHP file change by some other means, such as by using SFTP.” Health Check plugin returns: “The loopback request to your site took too long to complete, this may prevent WP_Cron from working, along with theme and plugin editors.” After trying all the suggestions, removing all plugins etc. the issue still remains. I have an exact mirror on my development machine where everything works fine, it’s just on the live site I’m getting the errors when editing a theme file direct. Hosts Heart Internet responded with: We prohibit loopback connections to the server, on security grounds, so that will explain the 2nd error message and may well be a contributing factor to the first. Can you check to see if WordPress have a workround for if the server prohibits loopback connections, and we can then assist you with resolving any problems. Any suggestions? WordPress 4.9. Theme php file editing.