[SITE-1972] php 5.3-5.5 eol release note

source/releasenotes/2025-01-15-php-53-55-eol.md

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+---
+title: "PHP 5.3 and 5.5 no longer available starting February 25, 2025"
+published_date: "2025-01-15"
+categories: [infrastructure, security, action-required]
+---
+As part of our continued effort to protect and secure customer sites, the Pantheon platform will no longer offer PHP versions 5.3 and 5.5 as of February 25, 2025.
+
+PHP 5.5 was declared end-of-life (EOL) by [the PHP Foundation](https://www.php.net/supported-versions.php) on July 21, 2016, more than eight years ago. EOL software does not receive security or feature updates, and could expose sites to attack if any vulnerabilities or exploits are discovered.
+
+We will soon provide long term support (LTS) security coverage for the remaining EOL versions of PHP on the platform.
+
+## Action required
+
+Customers with sites using PHP 5.3 and 5.5 should test and [upgrade the PHP version](/guides/php/php-versions) to at least PHP 7.2. If no action is taken, sites using PHP 5.3 and 5.5 will be auto-upgraded to PHP 5.6 on February 25, 2025. Pantheon [currently recommends](/guides/php#supported-php-versions) at least PHP 8.1 for all production sites.
+
+Sites created with custom upstreams using EOL PHP versions may also have unexpected behavior upon site creation.