Zen Cart® is made available to you for your use, addition, changes, modification, etc. without charge, under Version 2 of the GNU General Public License.
While we do not charge for this software, donations are greatly appreciated, each time you install a new version, to help cover the expenses of maintenance, upgrades, updates, the free support forum and the continued development of this software for your online E-Commerce store.
Donations can be made on the Zen Cart® Team Page
We appreciate your support.
The Zen Cart® Team
Zen Cart® v1.5.4 is compatible with PHP 5.2.10 through PHP 5.6, and MySQL 5.1 thru 5.6
(Note: security features are stronger when using PHP 5.3.7 or newer.)
(Note: PHP 5.2.x and PHP 5.3.x are deprecated and no longer supported by www.php.net ... You REALLY should be using PHP 5.5 if possible, for both security and speed benefits.)
This document only mentions the actual changes specific to 1.5.4. If you want to see the long list of 1.5.2-specific and 1.5.3-specific improvements, see the whatsnew_1.5.2.html and whatsnew_1.5.3.html files.
Simple: if you are using v1.5.3 already and have not customized any of the files listed in the changed_files-v1-5-4.html document, then simply replace those files with the new files as listed.
If you HAVE customized or altered certain files, simply re-do your customizations in the new version of those particular files by making the same changes needed.
If you are using Addons/Plugins that have made alterations to those files, it is best to compare those changed files against the original Zen Cart files for the version those plugins were built for, and see what changes were there ... and then re-build those changes in the v1.5.4 file.
If you are upgrading from a version OLDER than v1.5.3, then please do a standard complete site upgrade.
For a list of files that have been changed since v1.5.3, see the changed_files-v1-5-4.html document.