Blank pages can happen when you may have a PHP version wrong for the Zen Cart version you are using, or other applications that may conflict with each other. There can even be occurrences of this happening by simply installing, upgrading, or customizing your store. Each and every time you touch a PHP file, you will want to make sure that the code you are placing will not conflict with Zen Carts coding or applications.
In case you’re getting a blank page when attempting to search for a specific page on your store, or clicking on a link and it doesn’t do anything, you’ve probably got a PHP error in one of your files. You can check for errors by looking at either Zen Carts logs or the log entries being recorded in your servers control panel or /logs directory.
In some cases it happens because of an incomplete FTP file transfer where files are left unfinished. This happens more commonly in larger file transfers.
With Zen Cart is very important to make sure you double check your work before publishing to production as errors can be easily made and tricky to resolve if not knowing where to look.
If you do get these errors however, there is a convenient and easy to use tool built in to Zen Cart to log these errors. The Debug Error-Logging Tool can be found here.
Utilizing the Debug Error-Logging Tool, you will be able to see what’s going on with your site and continue to troubleshoot and search the errors you are getting. Some times the best rule of thumb is to revert any last changes you have made in order to bring your site back up.