Please keep in mind that implementing, diagnosing, and debugging a custom configuration for mod_pagespeed are tasks that are best handled by a systems administrator with the skills, training, and expertise required to do so for you. Although these tasks are not related to cPanel or the basic configuration of cPanel, we would like to offer the following guide as a courtesy.
This guide goes over some techniques that can be used to debug and diagnose problems that you may encounter when optimizing mod_pagespeed for use on your cPanel server.
Turning Debug Output on via the Configuration File
If you'd like to get debug output for every request, you can turn it on by enabling the debug filter in the configuration file with the following:
If you're not sure where you can put this configuration please review the following guide:
Turning Debug Output On Per Request
The mod_pagespeed module also allows you to enable, disable, and configure various options on a per request basis via GET parameters.
The following URL, when requested, would enable mod_pagespeed, enable the default optimizations, and produce debug output within the HTML of the page:
If you need more detailed information please see the official documentation: