PHP is the language WordPress itself is written in, so the PHP version running on your server sets a hard ceiling on your site’s speed and security — no plugin or theme choice can compensate for an outdated PHP version underneath them. WordPress officially recommends PHP 8.3 or greater; it will still technically run on PHP 7.4, but that version reached end of life years ago and no longer receives security patches of any kind.
Where PHP support actually stands right now
| PHP version | Status | Security support until |
|---|---|---|
| 7.4 and earlier | End of life — no patches at all | Already ended |
| 8.2 | Security fixes only | End of 2026 |
| 8.3 | Security fixes only | End of 2027 |
| 8.4 | Active support | End of 2028 |
| 8.5 | Active support (current release) | End of 2029 |
“Security fixes only” means the version isn’t getting new features or performance work anymore, but known vulnerabilities still get patched. Once a version passes its security-support date entirely, nothing gets patched — that’s the point at which running it becomes a real liability rather than just a missed opportunity.
What actually improves when you upgrade
- Real performance gains, not marketing language. PHP 8 introduced a JIT compiler and ongoing improvements to PHP’s internal opcode cache, and PHP 7.4 to PHP 8.x upgrades are consistently benchmarked as a meaningful speed improvement for typical WordPress workloads — this isn’t a “your mileage may vary” claim, it shows up in how fast pages generate on the server side.
- Patched vulnerabilities, not just newer features. Every PHP release fixes security issues discovered in prior versions. Running an end-of-life version means every one of those since-discovered vulnerabilities stays open on your server indefinitely, since there’s no patch coming.
- Plugin and theme compatibility going forward. Plugin developers increasingly write and test against current PHP versions. Staying several major versions behind means new plugin releases are more likely to silently misbehave or outright fail on your server.
- Lower memory usage per request. Each PHP major version has generally reduced memory overhead per request compared to its predecessor, which matters directly for how many concurrent visitors a given hosting plan can serve before slowing down.
What a PHP upgrade does and doesn’t change
A PHP upgrade is a server-side change — it doesn’t touch your site’s design, content, or URLs, and visitors won’t see any difference in how pages look. What it changes is how fast PHP executes the code behind those pages and which known vulnerabilities are patched. The only visible risk is indirect: if a specific plugin or custom code relies on a PHP function that was deprecated or removed in the new version, that plugin (not your content) can break until it’s updated or replaced — which is exactly why the compatibility check below matters more than the upgrade step itself.
How to check what PHP version your WordPress site is running
In your WordPress dashboard, go to Tools → Site Health → Info → Server — it lists your current PHP version directly, no plugin required. Most managed WordPress hosts also show this on the hosting control panel, usually under a “PHP settings” or “server” section.
Before you upgrade
- Check plugin and theme compatibility first. A handful of older or abandoned plugins genuinely break on newer PHP — check each active plugin’s “tested up to” PHP version before switching, not after.
- Test on staging, not live. If your host offers a staging environment (most managed WordPress hosts do), upgrade there first and click through the site’s core functionality before touching production.
- Back up before you touch anything. A full site and database backup immediately before the switch means a bad upgrade is a rollback, not an emergency.
- Upgrade one major version at a time if you’re several behind. Jumping from 7.4 straight to 8.5 compounds every version’s compatibility changes at once — stepping through 8.2 or 8.3 first makes it easier to isolate what broke if something does.
For the actual upgrade steps once you’ve confirmed compatibility, the walkthroughs for upgrading to PHP 8.4 on Ubuntu and upgrading to PHP 8.5 on Ubuntu cover the Sury/Ondrej PPA setup, Apache and Nginx configuration, and the extension and troubleshooting steps specifically.
Once PHP is current, it’s worth running through the WordPress technical audit checklist to confirm the rest of the site is in similarly good shape, rather than treating the PHP upgrade as a one-off fix.
If you’d rather have someone else handle the upgrade end to end — compatibility check, staging test, and the switch itself — that’s covered under WordPress maintenance and care plans.
