Uncaught SoapFault exception: [HTTP] Error Fetching http headers
This error can appear on the client if there is a problem on the server side. For example, if the SOAP server is a PHP script with a parse error, the client will fail with this message.
If you are in control of the server, tail your Apache error_log on the machine that hosts the SOAP server. On CentOS you will find this in /var/log/httpd/error_log, so the command is:
tail -f /var/log/httpd/error_log
Now refresh the client and watch for the error message. Any PHP errors with the server script will be shown.
Hope that helps someone.