WordPress core is usually fine on newer PHP. Plugins (and sometimes themes) are the typical failure point. This guide explains what changes in PHP upgrades and how to reduce breakage.
What changes in PHP upgrades
- Deprecated features are removed
- Stricter typing and error handling
Why plugins break
- Unmaintained or abandoned code
- Assumptions about old PHP behavior
- Use of deprecated functions or extensions
Mitigation
- Test upgrades on a staging or clone first
- Inventory critical plugins and check compatibility
- After upgrading, follow debugging WordPress after a PHP upgrade if something breaks
FAQ
Should I upgrade PHP on production without testing?
Prefer testing in staging or on a clone. If you must do it live, have a rollback plan (e.g. switch PHP-FPM pool back) and be ready to disable plugins via filesystem or WP-CLI.
One plugin broke; can I just update that plugin?
Often yes. Update the plugin (or replace it) and re-enable. If the plugin is abandoned, consider replacing it or patching locally and documenting the risk.
Related
- Debugging WordPress after a PHP upgrade — isolate the broken plugin
- Safer plugin updates on production WordPress — update discipline