PHP 500 Error on IIS: How to Find the Real Cause

The problem

A generic 500 response hides the actual PHP or IIS error.

Recommended approach

Temporarily enable controlled error logging in a safe environment and inspect IIS/PHP logs instead of exposing errors publicly.

Step-by-step checklist

1. Record the exact request URL.
2. Check IIS logs.
3. Check PHP error logs.
4. Validate configuration and file permissions.
5. Fix the root error and restore production-safe error handling.