Zen CartI was recently preparing the launch of a new Zen Cart store for a client when encountered a blank page on checkout. There was no error, just a blank page. Baffled, I reloaded the CHECKOUT page and processed another test transaction only to see the blank page appear farther up the checkout process on the CART page.

The admin showed the orders were being processed, so the data was hitting the database. I had no where to go, and was looking at either systematically going through each template file and each database table to see if I could find any evidence of what was causing the errors.

The more I thought about doing this the reality of the tedious hours it would take to just find it began to sink in. I did research and found other developers that had encountered this issue, but none seemed to offer any clear path that would fix my issue. Basically they were even more lost than I was on the blank page horror.

Finally I found the Zen Cart Error-Logging Utility. This little app saved the day and boosted my confidence for future Zen Cart installs. First, the download page explains that the blank page effect is the result of PHP syntax errors. This can happen by tinkering around in the template files and mistyping an operator. Ok, that sounded good. However, I had purposely set my customizations from the admin just for this reason.

Apparently Zen Cart version 1.3.8 has this bug. It’s recommended to upgrade to 1.3.8a, which I had already done. I was still getting the error.

I proceeded to download and install the Debugging Tool per their instructions.

I ran the transaction again and returned this error in the log file

  • [04-Apr-2008 13:34:22] PHP Warning: Cannot modify header information - headers already sent by
    (output started at /home/broadcas/public_html/catalog/includes/languages/
    english.php:1401)
    in/home/broadcas/public_html/catalog/includes/init_includes/
    init_templates.php on line 78
  • [04-Apr-2008 13:34:22] PHP Warning: Cannot modify header information - headers already sent by
    (output started at /home/broadcas/public_html/catalog/includes/languages/
    english.php:1401)
    in /home/broadcas/public_html/catalog/includes/functions/
    functions_general.php on line 44\

I replaced these files and thought I got it working until the confirmation page came up blank. After more research I discovered that functions_general.php is not the correct file to swap, it’s english.php in the languages file. At this point I just uploaded the whole damn languages folder from a fresh download of Zen Cart 1.3.8a. Boom! it all worked. It tested and retested with no errors.

If you run into this issue, or any other Zen Cart weirdness, please download this file. It will save tons of time and frustration, when you need to squash little pain-in-the-ass bugs like this.