I’ve been contacted recently by a number of Zen Cart users who are experiencing on occasion, an error similar to the following while working in the administrative section of their sites.
Catchable fatal error: Object of class queryFactoryResult could not be converted to string in … html_output.php
The problem you are experiencing stems from leftover legacy code that is incompatible with PHP5.
Here are two links that will help you understand and correct the issue.
//www.zen-cart.com/forum/showthread.php?t=90739
//www.zen-cart.com/forum/showpost.php?p=487734&postcount=11
An interim workaround has been provided by the Zen Cart team. The link to the files which solve this issue are provided here.
//www.zen-cart.com/forum/showpost.php?p=487360&postcount=10
I came across this error a few weeks ago when we upgraded our server to PHP5. We just went back to PHP4. Is there a reason to use PHP5 with Zen Cart?
There are many reasons to use PHP5 in general. PHP4 is not being actively supported anymore and 5 is more secure. You can still use and get 4 but eventually it is wise to upgrade.
As far as Zen Cart is concerned, the current version does not require PHP5. However, when the next major release comes out (1.4) you will be required to use PHP5. the next release uses object oriented programming and I believe utilizes some functions that are only present in PHP5.
So, if you want to upgrade whenever that next release is available, you will need PHP5.