We default to PHP 8.3 for new WordPress installs. That's the right answer for almost every site. Older versions (7.4–8.2) are available for compatibility with legacy plugins and themes.
Why 8.3
- Faster — PHP 8.3 is roughly 30–50% faster than 7.4 on typical WordPress workloads.
- Better memory usage — uses less memory per request.
- Modern features — JIT compilation, typed properties, named arguments, readonly classes.
- Active support — security patches and bug fixes.
- Best WordPress compatibility — WordPress 6.4+ runs on 8.3; most actively-maintained plugins work fine.
When you'd use an older version
- Legacy plugin or theme that hasn't been updated. Some old plugins fail on PHP 8.x — they use removed functions or syntax that's been dropped. If a plugin is essential and hasn't been updated, you may need to keep PHP 7.4 (or a specific 8.x) for compatibility.
- Custom code in your theme or
mu-pluginsthat hasn't been audited for newer PHP. - Hosting migration in progress where you're moving from a host that ran an older PHP version and you haven't tested 8.3 yet.
How to switch
- Go to Services → click hosting → PHP Version tile.
- For each domain, pick the PHP version you want.
- Save.
The switch is instant. You can switch back as easily if needed.
Test before switching production
If your site is mission-critical, test before flipping the version:
- Set up a staging copy at a subdomain and switch its PHP version first.
- Run through the site — admin login, all critical user flows (checkout, contact form, etc.).
- Watch for errors in
wp-content/debug.log(turn on WP_DEBUG temporarily).
If staging works, switch production with confidence.
What PHP versions are supported by WordPress core?
WordPress maintains a list at wordpress.org/about/requirements/. Currently:
- PHP 7.4 minimum for WordPress 6.x.
- PHP 8.3 recommended.
- Older PHP versions still receive WordPress security patches but new features may not work.
For new installs, default to 8.3. For existing installs, plan an upgrade path.
Plugin and theme compatibility
When considering a PHP version upgrade:
- Check each plugin's "Tested up to PHP" version on its WordPress.org page.
- For paid plugins, check the vendor's docs.
- For custom code or your theme, a developer should audit. Common breakage:
each()removed in 8.0.count()on null is fatal in 8.0+.mysql_*functions removed (deprecated since PHP 5.5).
If you have an old custom theme, the audit + cleanup may take a few hours. After that, you're on a faster, safer base.
"My site shows a fatal error after PHP version change"
Roll back the PHP version on the same page. The site comes back to working state immediately.
Then debug what's incompatible:
- Turn on
WP_DEBUGinwp-config.php. - Switch PHP version up again.
- Check
wp-content/debug.log— the fatal error tells you which file is broken. - Update the plugin/theme, or fix the custom code.
Or, if the offender is a specific plugin, disable just that plugin and try the upgrade again — many sites can run on 8.3 with one or two plugins disabled.
What about PHP 8.4 or 9.0?
PHP 8.4 (released late 2024) has limited WordPress plugin support so far. WordPress 6.x officially tested up to 8.3.
We'll add 8.4 as an option once WordPress and major plugins broadly support it. Check the PHP version dropdown periodically — newer versions appear there as they're added.
Power-user note
For ultimate performance, run your site on the newest PHP your stack supports. Each major PHP release improves performance by 20–40%. Combined with our LSCache + Redis setup, modern PHP makes WordPress dramatically faster than legacy stacks.
If you're optimizing for absolute speed, PHP 8.3 + LSCache + Redis on Flashcloud's NVMe storage is roughly 3x faster than PHP 7.4 + WP Super Cache + no object cache on a typical SATA SSD shared host.