However, the technology behind PHP 5.1 is outdated and only a small number of websites still use it. We are officially end of life-ing our support for PHP 5.1. If you check the PHP.net end-of-life schedule, it's been dead upstream for almost 17 years.
We will not be patching security vulnerabilities in PHP 5.1 beyond Apr 1, 2024 If you use PHP 5.1, watch for the date.
PHP 5.1 (alt-php51) will still be available for current platforms, but it will not be available for all the future platforms like CentOS (HardenedPHP) and CloudLinux. Right now, this doesn’t apply to Ubuntu and Debian.
To remove alt-php51 use the following command:
yum remove alt-php51*
We offer HardenedPHP with both Imunify360 and CloudLinux.