As of May 15th, 2025, with the release of Backdrop CMS version 1.31.0, Backdrop CMS will require PHP version 7.1 or greater.
Currently, the listed requirement for Backdrop CMS is PHP 5.6 or greater, a version of PHP that has long since reached the end of its official life.
Philosophically, the Backdrop community aspires to maintain as much backward compatibility as possible and is committed to running on affordable hosting with very basic requirements. Our policy has been to support the oldest still-supported version of PHP provided by a Linux distribution. As we look forward to providing support for the latest available release of PHP (version 8.4) our core team has determined that it is not possible to provide support for PHP 8.4 while at the same time providing support for versions older than 7.1. See the core issue tracking PHP 8.4 support for more information.
If your Backdrop site is running on a version of PHP older than 7.1, please look into options for upgrading or moving to a new server. Your site admin can find the version of PHP your site is using on the Status Report page (/admin/reports/status). Before upgrading PHP, make sure that you have upgraded to the most recent version of Backdrop Core and that all of your contributed modules and themes are up to date. Backdrop Core is currently compatible with PHP 8.3.
The benefits of this change to the Backdrop CMS community include:
- We will be able to make Backdrop run on PHP 8.4 and higher without any deprecation warnings or notices.
- It is easier for us to keep Backdrop up-to-date if we don't have to ensure that all changes are compatible with so many versions of PHP.
- Newer versions of PHP are more secure and faster.
How does this affect Backdrop CMS sites running on older versions of PHP?
Beginning with version 1.31.0 of Backdrop CMS on May 15th, 2025, Backdrop will no longer run on PHP 5.6 and 7.0. You will still be able to run Backdrop on older versions of PHP as long as you do not update your site. Failure to update your Backdrop site will mean missing out on new bug fixes, feature improvements, and security updates.
When did Backdrop CMS last change their PHP support?
As of May 15th, 2022, with the release of Backdrop CMS version 1.22.0, Backdrop CMS dropped support for PHP versions less than 5.6.
If you have questions about this change, please post a question in the forum.