Cloudflare Error 1020: Access Denied by Firewall Rule

Symptom

Specific visitors (or you) get 1020; others are fine.

Root cause

A WAF custom rule or IP Access Rule is blocking their IP or ASN.

Fix, in order

1. Find the matching rule in Security EventsDashboard > Security > Events > filter service=Firewall
2. Whitelist the legit IP or fix the expression(ip.src eq 203.0.113.10)
3. Check country rules if the user is on VPN# VPN exits often trip country blocks

Prevent it coming back

Every block rule needs an exception path and monitoring.

Run it on clean infra

Spinning up a fresh box to reproduce or escape this error?

Build apps without servers

Related

Cloud & DevOps tool comparisons · Hardware build guides

NinjaOps publishes free engineering guides. Some outbound links are affiliate links: they cost you nothing and support the site.

Last reviewed 2026-10-02 · NinjaOps SEO grid · DevOps blog