If you’ve ever seen something in WordPress like “Warning: require_once(/public_html/wp-admin/includes/ajax-actions.php) [function.require-once]: failed to open stream: No such file or directory in /public_html/wp-admin/includes/ajax-actions.php on line 33″ don’t let it freak you out.
“Failed to Open Stream” is a PHP error that simply means the file doesn’t exist or isn’t usable (which is the case when the permissions don’t let a file be read).
Fire up your favorite FTP client (like FileZilla) and make sure the file is present in the remote view. The error message will tell you where to look. In this example, we’d just look for /wp-content/wp-admin/includes/ajax-actions.php.
If the file isn’t there, upload it and make sure you can see it. We’ve seen FileZilla and GoDaddy get into trouble when one or the other believes it sees something as malware. Screenshot of the FTP log below.
It didn’t, but we had to dump the install and start again just to get it taken care of.
If the file IS there, make sure it’s permissions are set correctly. Here are the recommended WordPress permissions scheme. Set them accordingly and you should be good to go.
See, that scary error message wasn’t so scary after all.