The Correct Way to Bind a Custom Domain in Cloudflare Workers

TL;DR In wrangler.jsonc, use custom_domain: true in routes with only the hostname as the pattern — no /* wildcard

Table of Contents

TL;DR
Context
The Problem
The Fix
Why This Happens
What I Learned
References

TL;DR

In the routes config, set pattern to just the hostname — no /* — and pair it with custom_domain: true.

Context

After deploying a blog to Cloudflare Workers, I wanted to bind quidproquo.cc to replace the default *.workers.dev URL.

The Problem

I added the following to wrangler.jsonc:

"routes": [
  { "pattern": "quidproquo.cc/*", "custom_domain": true }
]

Running wrangler deploy threw an error:

Invalid Routes:
  quidproquo.cc/*:
  Wildcard operators (*) are not allowed in Custom Domains
  Paths are not allowed in Custom Domains

The Fix

For a custom domain, the pattern should be just the hostname — no paths or wildcards:

"routes": [
  { "pattern": "quidproquo.cc", "custom_domain": true },
  { "pattern": "www.quidproquo.cc", "custom_domain": true }
]

After making this change, you need to run astro build again — the Cloudflare adapter copies the config into dist/server/wrangler.json, so running wrangler deploy directly will use the stale file from the previous build.

Why This Happens

Custom domains and route patterns are two distinct mechanisms. A route pattern like example.com/* is for zone-based routing and performs path matching. A custom domain, on the other hand, points the entire hostname directly at a Worker — paths are neither needed nor permitted.

What I Learned

When using custom_domain: true, the pattern is just the hostname. Adding a path breaks it. And any time you change wrangler.jsonc, you need to rebuild before deploying.