Earlier I was working on a Zen Cart site and ran into an issue installing the Ultimate SEO URL add-on. The Ultimate SEO URL add-on creates more SEO(Search Engine Optimization) friendly URL’s for Zen Cart. The site in question already had a previous version of the Ultimate SEO URL add-on installed and once I was finished the front-end of the site was working perfectly with the new SEO friendly URL’s. The problem was when I attempted to login to the admin portion of the Zen Cart site I was receiving a “500 – Internal Server Error” message. Below I have noted information on what was done to troubleshoot the problem as well as how the problem was resolved.
The error in the title causes all pages on a ZenCart installation to display this followed by a SQL select statement. The error is related to the Ultimate SEO URL’s ZenCart addon. The issue could be caused by one of two things which are the SEO URL cache is corrupted for some reason or the installed version of Ultimate SEO URL’s is old.
Error: 1054 Unknown column ‘c.parent_id’ in ‘on clause’