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Sweep 22 Oct 2026 · 04:32Z Build v2.1.308 527 read Stable v2.1.308 Latest v2.1.308 Next v2.1.308 Feeds RSS JSON llms.txt llms-full.txt Unofficial
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Claude Code v2.1.227 ·

Bad HTTP header values are rejected before the request instead of crashing

Illegal header values from your env or key helper now fail clearly instead of crashing.

You'll notice Improvements
JSON All of v2.1.227
You'll noticeTier: how much it should matter to you
3Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
AuthArea: what it touches
ImprovementsKind: in v2.1.227,
ImprovementsSection of the release
What

If a header value coming from ANTHROPIC_CUSTOM_HEADERS, an API key environment variable, or apiKeyHelper is not a legal HTTP header value, Claude Code now fails with a clear error before sending, classified as your mistake rather than an internal crash.

Details
  • New InvalidRequestHeaderValueError, classified as invalid_request_header or invalid_api_key when the value is user-supplied.
  • Logged at error level rather than reported as a crash.
  • Treated as non-retryable during API key verification, so a malformed key value fails immediately.
  • The error class does not exist in v2.1.226.
Evidence

request header value rejected before send: not a valid HTTP header value

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

Read from
Names in the bundleANTHROPIC_CUSTOM_HEADERSapiKeyHelper

See this entry in the whole of v2.1.227 →

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