Observed Signal · Aug 5, 2026 · Technical Issue · Source: DEV Community · Impact: 2/5 · Sentiment: Neutral
Cloudflare Worker wildcard route caused R2 custom domain 404
A developer's R2 bucket served via a custom domain returned 404s even though the bucket, DNS, and custom domain were healthy. The cause was an existing Cloudflare Worker route with a wildcard pattern that matched the subdomain; the Worker ran first, looked for the asset, and returned the site's 404 page before R2 could respond. The fix was to remove the wildcard route and enumerate the specific hostnames the Worker should serve (for example example.com/* and www.example.com/*). The post also shows a quick diagnostic (check Content-Type via curl) and warns that Cloudflare product dashboards report each product's health independently, which can hide cross-product routing conflicts.
Practical operational warning for engineers using Cloudflare Workers and R2: routing precedence can silently intercept requests and cause misdiagnosed 404s. Relevant to teams deploying edge workers and object storage custom domains but not industry-shifting.
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Key Takeaways & Evidence Grounding
- Requests to the R2 custom domain (media.example.com) returned 404 despite the R2 bucket, files, custom domain, and DNS being correctly configured.
- A Cloudflare Worker route using a wildcard pattern (e.g., _.example.com/_) matched the subdomain and took precedence over the R2 custom domain, causing the Worker to return the site's 404 page.
- R2 never received the requests because Workers routing precedence intercepts matching requests before R2.
- Quick diagnostic: curl -sI https://media.example.com/some-file.mp4 — if Content-Type is text/html for a video file, the request is not reaching R2.
- Fix: stop using a wildcard Worker route and explicitly enumerate hostnames the Worker should serve (e.g., example.com/*, www.example.com/*).
Connected Companies & Entities
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Ontology Mapping & Concepts
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