What Is PHP (and Why Version Upgrades Break Sites)?
Updated 16 October 2026
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PHP is the programming language that runs most of the web's back end, building each page on the server before it reaches the browser. WordPress, which powers about 40% of all websites (W3Techs, October 2026), is written in PHP. Upgrading to a newer PHP version can break a site when an old plugin or theme still relies on code that version removed. Keeping PHP current is a security necessity, but it needs testing on a copy first.
What is PHP and what does it do?
PHP is a server-side scripting language, which means it runs on the web server rather than in the visitor's browser. The official project defines it as "a widely-used open source general-purpose scripting language that is especially suited for web development and can be embedded into HTML" (php.net).
Here is what happens on a request. The server runs the PHP code, pulls content from the database, assembles the finished HTML, and sends that to the browser.
The visitor never sees the PHP itself, only the page it built. This is what makes a site dynamic, able to show different content to different people, rather than a fixed static page.
Why PHP matters for a WordPress site
PHP matters because WordPress, WooCommerce, and almost every WordPress plugin and theme are written in it. Your hosting runs a specific PHP version, and that version should meet what WordPress recommends.
WordPress currently recommends "PHP version 8.3 or greater" (WordPress.org, May 2026), along with a modern MySQL or MariaDB database. It still runs on PHP 7.4 and up, but WordPress flags those older versions as past end of life.
If your hosting runs an older version, WordPress and its plugins may misbehave or refuse to update. That is why the PHP version buried in your hosting settings quietly matters more than most owners realize.
Why upgrading PHP can break a site
Upgrading PHP breaks sites when old plugin or theme code uses functions the new version has removed. Each major PHP release retires outdated features, and any plugin still calling them stops working, sometimes with a blank white screen or a 500 error.
The mechanism is worth understanding. The PHP upgrade itself is rarely the problem; the real cause is a plugin or theme that was never updated to match.
This is the same pattern behind why website updates break things in general. It is also exactly why you test a PHP change on a staging site before touching the live one. On a copy, a broken plugin is a quick fix. On a live store, it is lost sales.
Which PHP version should you be on?
You should be on a PHP version that still receives security support, and ideally one in active support. PHP releases move through active support, then security-only support, then end of life.
| PHP version | Status (php.net, Oct 2026) |
|---|---|
| 8.4 and 8.5 | Active support (8.4 until 31 Dec 2026) |
| 8.3 | Security support only |
| 8.2 | Security support until 31 Dec 2026 |
| 8.1 and older | End of life, no more patches |
Source: php.net, Supported Versions (checked October 2026).
Running an end-of-life version is the real risk. As WordPress warns, PHP 7.4 and other legacy versions "have reached their official End Of Life and may expose your site to security vulnerabilities".
The first thing we check on a slow or erroring inherited site is which PHP version the hosting runs. Many sit years behind on a release that stopped getting patches long ago.
Frequently asked questions
Do I need to know PHP to run a WordPress site?
No. You can build, edit, and run a WordPress site entirely through its dashboard without ever seeing PHP. Knowing PHP only matters if you want to customize themes or plugins at the code level. For everyday use, PHP runs quietly in the background, and your only job is to keep it on a supported version through your hosting.
How do I know which PHP version my site uses?
Check your hosting control panel, which usually has a "PHP version" or "PHP selector" tool, or look at WordPress's built-in Site Health screen under Tools. Both show the version your site runs on. If you are unsure how to read it or change it safely, your host's support can tell you, and a developer can upgrade it with proper testing.
Is it safe to upgrade PHP?
Yes, and it is necessary for security, but test it on a copy of your site first. Upgrade the staging copy, check that every page and form still works, then apply it live. Most upgrades are smooth; the ones that break involve an old plugin or theme. Updating your plugins and themes before the PHP upgrade removes most of the risk.
What happens if I stay on an old PHP version?
Your site keeps running for a while, but the risks grow. An end-of-life PHP version stops getting security patches, so known flaws never get fixed. Over time, plugins and themes also drop support for it. Staying on old PHP trades a small upgrade job now for a larger security and compatibility problem later.
Why did my site go blank or show a 500 error after a PHP upgrade?
A plugin or theme on your site used code the new PHP version removed, so it crashed the page. The fix is usually to roll back to the previous PHP version, update the offending plugin or theme, then try the upgrade again. This is why the change belongs on a staging copy first, where a crash affects nobody. A developer can pinpoint which plugin caused it from the error log.
Is a newer PHP version faster?
Sometimes, but don't upgrade for speed alone. PHP's own PHP 8.0 release notes say its new JIT compiler is much faster on synthetic benchmarks, but that typical application performance is "on par with PHP 7.4". The gain varies by site, so measure before and after on staging. Security support is the reason to upgrade; any speed gain is a bonus.
Keeping PHP current without breaking things
Storming Solutions builds custom-coded websites and maintains existing WordPress sites for Malaysian businesses, and keeping PHP on a supported, tested version is part of that upkeep. We upgrade on a staging copy first, fix any plugin that complains, then move it live. A surprise white screen on a working site is not a risk worth taking.
Not sure what PHP version your site runs, or whether it is safe to upgrade? Ask on WhatsApp or bring it to our web development work. We will check the version, test an upgrade safely, and keep your site both current and stable.