WordPress has officially ended support for PHP 5.2 – 5.5 and bumped its minimum required PHP version to 5.6. The plan announced last December was to bump the minimum required version in early 2019 and, depending on the results, bump it again to PHP 7 in December 2019. Sites on PHP 5.5 or earlier can still get security updates but will not be able to upgrade to the latest major WordPress version.
Today only 2% of WordPress sites remain on PHP 5.2. Roughly 20% are on versions 5.5 or earlier. Nearly half of WordPress installs are on PHP 7.0+.
Although PHP 5.6 is the new minimum required version for running WordPress, the project’s technical requirements page recommends users ask their hosts for PHP version 7.3 or greater. PHP 7+ offers massive performance gains for users and developers will be able to update their plugins to use more modern syntax.