A PHP version mismatch can break a site when the application requires a newer runtime or still depends on older syntax removed in modern PHP releases.
Common symptoms
- The site worked before changing PHP version
- You see syntax or fatal compatibility errors
- One application breaks while others in the account still work
Troubleshooting steps
- Check the application's documented PHP version requirements before making further changes.
- Use cPanel's PHP selector or MultiPHP tool to switch the affected domain to a compatible version if available.
- Review the exact error message to identify whether the application itself or a plugin/module is incompatible.
- Update the application and extensions to versions that support your target PHP version.
- Do not leave production sites on end-of-life PHP longer than necessary; plan an upgrade path after restoring service.
Additional notes
- A plugin can be the real incompatibility even when the core application supports the newer PHP version.
- Mixed environments with multiple domains can run different PHP versions depending on hosting configuration.
When to contact support
Contact support if the site remains broken after moving to a vendor-supported PHP version.