I was required to install the Module Manager add-on for Zen Cart because it is required by the Simple SEO URL Zen Cart add-on requested by a client of mine. During the install process you visit the Module Manager section in the Zen Cart admin and I received an error complaining that a specific file did not exist. Below is a quick description of the error and what was done to resolve it.
A couple days ago I installed the Zen Cart Simple SEO URL add on for a client of mine. The SSU Zen Cart admin page was blank after following the instructions attempting to trigger the final installation steps by visiting a specific page in the Zen Cart admin. It appears I missed reading the “requirements” section of the installation instructions. Below is more information on the problem and how to easily resolve.