Check WordPress PHP version, extensions, and memory

When to use this guide

Use this when WordPress fails after changing PHP version, updating plugins or themes, moving hosts, or seeing fatal errors about memory, missing extensions, missing classes, or incompatible syntax.

Safety notes

• Do not increase memory limits blindly if logs point to a plugin loop or runaway import.
• Match PHP settings between CLI and the web runtime before trusting command output.
• Keep the previous PHP version available until the site is tested.

Basic steps

1. Check the PHP version used by the web server or hosting panel.
2. Compare plugin, theme, and WordPress core requirements against that version.
3. Review wp-content/debug.log, PHP-FPM logs, or hosting PHP error logs.
4. Check common extensions such as mysqli, curl, mbstring, xml, zip, intl, and gd when logs mention missing functions.
5. Adjust memory only after a log confirms memory exhaustion.
6. Retest the failing URL and wp-admin.

Expected result

The active PHP runtime should match the site requirements, required extensions should be loaded, and the original fatal error should either disappear or narrow to a plugin or theme that needs rollback.

Next links

• Capture WordPress-level errors with Enable WordPress debug log safely.
• If the page is blank, use Fix WordPress white screen without wp-admin access.
• Compare web server logs with Check access and error logs for HTTP failures.