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DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

← All of v2.1.238 Home All releases ←olderv2.1.237 v2.1.239newer→

Claude Code v2.1.238 20 Aug 2026

Proxy refusals no longer look like Anthropic blocking you

You'll notice

Useful4 Signal2

Internals

Proxy tunnel refusals now name a CDN, VPN or firewall instead of looking like an Anthropic block.

What

When a corporate proxy or CDN refuses the CONNECT tunnel, the error now says so instead of surfacing as an Anthropic 403. The failure carries code ERR_PROXY_TUNNEL plus the CONNECT status and headers, and the explanation names a CDN or a VPN/firewall refusing the request before it reached Anthropic.

Details

A classifier inspects request-id, cf-ray and server headers to label the refusal as coming from the origin, a Cloudflare-like intermediary, or some other intermediary.
Header sniffing gained a separate x-proxy-error reader alongside the existing x-deny-reason.
Reachable in this build with no flag.

Evidence

ERR_PROXY_TUNNEL

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.238 →