What specific Cloudflare settings might indirectly cause a 500 error on the free plan?

While rare, certain Cloudflare free plan settings could indirectly contribute. For example, a poorly configured Page Rule that forces HTTPS incorrectly or modifies headers in a way your origin server can't handle might trigger an error. Similarly, aggressive WAF (Web Application Firewall) rules, if misconfigured, could block legitimate requests leading to unexpected behavior on the origin. Always start by checking your origin server logs.