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WordPress is nagging me to upgrade PHP version!
Background
PHP is the programming language behind several popular website technologies. Websites that are co-housed together on the same server will all be using the same PHP version.
Upgrading from PHP 5.x to PHP 7.x changed a significant number of language constructs, such that some porting effort is generally needed to update a legacy website to PHP 7. PHP 7 confers a number of long needed advantages over PHP 5 - a significant performance boost, and significant security enhancements to make it easier to write safe and secure code. Rolling out PHP 7 was significantly difficult in the context of many websites - plugins and themes needed to be tested for whether they would function in the new environment, and a large fraction of themes written for PHP 5.x versions needed porting effort before they could be used on PHP 7.x environments.
Within the PHP 7.x series, most of the point releases are tightening the rules from warnings to fully depreciating legacy constructs. If a site is already running PHP 7.1 or greater there is no need to panic about updating it to PHP 7.4, no matter what WordPress says. WordPress is essentially putting up cosmetic warnings about PHP version well ahead of any technical need.
The support dates (and even the recommended schedule) for the core of a CMS (such as WordPress) are often less important for driving the PHP version choice, than the ecosystem of third party plugins and themes that are in use. A website may easily get stuck at an older version, if a needed theme or plugin can't tolerate a newer PHP version, regardless of what the core CMS supports.
Versions
| PHP Version | Notes & CMS Environments | Where to find it |
|---|---|---|
| 7.4 | This is the current upstream version, requested by WordPress & Drupal9 | Only available internally by special arrangement |
| 7.3, 7.2 | WordPress, Drupal7, Drupal8 and Drupal9 should all run adequately here, however WordPress and Drupal9 will warn about the old version | Current generation (RHEL7) Managed Servers, SIPB Scripts Fedora 30 cluster |
| 7.1, 7.0 | Early 7.x versions do not differ very significantly from each other; these generally can and should be upgraded to PHP 7.3 | |
| 5.6 | Drupal7 that's still here may not upgrade easily; most modern WordPress themes will not run, but WordPress core may run | Available on current generation Managed Servers, not recommended |
| 5.5 | WordPress on this PHP version cannot be upgraded to current WordPress releases | RHEL6 (legacy) Managed Servers, SIPB Scripts Fedora 20 cluster |
| 5.4, 5.3 | Apps running on these versions will need considerable porting effort | RHEL5 (legacy) Managed Servers |
Managed Server Environment
Current generation (2016-2021) servers installed at RHEL7, can easily run any of PHP 5.6, 7.2, 7.3; we can switch between them (at your request) without significant downtime. This includes most WordPress sites that are hosted by IS&T.
Noting, this doesn't include PHP 7.4, which WordPress warns about. Application Delivery does not have an ETA for providing PHP 7.4 to all customers. For servers that are currently at PHP 7.2, we can upgrade them in place to PHP 7.3, but we are not doing that proactively, since the differences are very minimal indeed.
Previous generation servers installed at RHEL6 cannot run PHP 7, and customers using legacy generation servers should be immediately offered an upgrade target if they are actively working on their website.
For a website running under PHP 5.5 or PHP 5.6, it will usually function adequately on an RHEL7 server running PHP 5.6, at which point the PHP version upgrade can be managed in place. For a website running under PHP 5.3 or PHP 5.4, it's frequently the case that it will require porting effort to even run under PHP 5.6, and it's thus stuck on the older version pending a full rewrite or similar development effort.
Requests
For websites on Managed Servers, we're happy to discuss the above issues; please write to ops-help@mit.edu and include the URL of the website in the subject.
SIPB Scripts
The SIPB Scripts team has provided support for moving an individual SIPB Scripts site from one PHP environment to another, as they have multiple clusters of backend servers. See: Can you update the version of PHP running on Scripts
Their "Fedora 30" environment will give you PHP 7.3, while their "Fedora 20" environment is at PHP 5.5.
As a reminder, IS&T can't offer any detailed support for working with SIPB Scripts, this is a project run by SIPB.
