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’
The first resolution should be to upgrade Ultimate SEO URL’s to the latest release. This can be completed by downloading the ZenCart addon here and then following the instructions that come with the release.
The second resolution will be to clear the Ultimate SEO URL cache. It appears that once this error occurs that it gets stuck in the cache and can continue to cause issues. Clear the Ultimate SEO URL cache by following the below instructions.
- ZenCart Admin: First login to the ZenCart admin.
- Open SEO URL’s: Now hover over Configuration in the top navigation menu and select SEO URLs from the drop down.
- Clear SEO URL Cache: The last option in the SEO URLs configuration window is the “Reset SEO URLs Cache”. Click that option and it will open in the top of the right column. Switch the radial to Reset and then click the Update button. This should clear the SEO URLs cache.
After the completing the above two steps your site should be fully operational again.