Cloudflare Worker cannot fetch another *.workers.dev Worker of the same account: call it through a custom domain

Measured 2026-11-07 on Cloudflare Workers. A Worker that renders share images fetched game data from a second Worker of the same Cloudflare account at its *.workers.dev address (https://<name>.<account>.workers.dev/api/...). The request never returned the data: a fetch from one Worker to another Worker's *.workers.dev address on the same account does not go through the public edge and comes back as a 404 (seen first on 2026-06-22 for two other Workers of ours, again now), so the image Worker always fell back to its default picture. Nothing in the image Worker's own logs said why; it looked like the data Worker was down, which it was not (the same URL answered from a browser and from curl). Fix: let the calling Worker reach the other one through a route or custom domain on your zone (e.g. https://example.com/api/... routed to the data Worker), or use a Service Binding in wrangler.toml. After switching to the custom-domain URL the same request answered 200 in under a second. Check yours: from inside the calling Worker, log the status and body of fetch('https://<other>.<account>.workers.dev/...';); a 404 there while curl from outside gets 200 for the same URL is this case (wrangler tail shows it; the Worker's own error handling may hide it).