What a PHP version conflict is #
WordPress runs on PHP, a server-side programming language. Your hosting provider controls which PHP version runs on your server, and plugins and themes are written to work with specific PHP versions. When the PHP version on your server changes (either because your host updated it, or because you updated it yourself), a plugin or theme that was fine before can throw Fatal Errors because it uses code that was removed or renamed in the newer version.
The symptom is usually a white screen or “critical error” message that appeared right after a PHP version change, or after a plugin update that introduced code written for a different PHP version than your server is running.
How Loupely identifies PHP version conflicts #
PHP version incompatibility produces specific error patterns: calls to undefined functions (functions removed in the new PHP version), deprecation notices that became Fatal Errors, or syntax errors from code that was valid in an older PHP version but isn’t in a newer one. Loupely captures these as PHP Errors and the diagnosis will name the specific plugin file and function that’s failing. This is significantly faster than the standard approach of deactivating plugins one by one until the error disappears.
Checking your current PHP version #
You can find your site’s current PHP version in Tools > Site Health > Info > Server. WordPress also shows a notice in the admin dashboard if your PHP version is below the minimum recommended version. The recommended PHP version for WordPress as of 2026 is PHP 8.2 or 8.3. PHP 7.x versions are end-of-life and no longer receive security updates.
What to do if a PHP update broke something #
If you or your host upgraded PHP and something broke immediately:
- Run a Loupely diagnosis to identify which plugin is throwing the PHP error.
- Check whether an updated version of that plugin is available that supports the new PHP version. Update it if so.
- If no update is available and the plugin is essential, temporarily revert to the previous PHP version through your hosting control panel (usually under cPanel or Plesk > PHP Manager). This buys time to find a replacement plugin or wait for the developer to release a compatible version.
- If the plugin is abandoned (no updates in over a year), find a supported alternative. Running code that isn’t compatible with current PHP is a security risk, not just a stability one.
What to do before upgrading PHP #
Before upgrading PHP on a live site, run the WP Engine PHP Compatibility Checker plugin. It scans your installed plugins and themes for known incompatibilities with the target PHP version and flags the ones that need attention before you make the switch. Test on a staging site first when possible. Going from PHP 7.4 to PHP 8.x is a significant jump and is worth testing before applying to production.