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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 v2.1.227 Home All releases ←olderv2.1.226 v2.1.228newer→
Claude Code v2.1.227

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

You'll notice
Useful3 Signal1
Auth

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

ANTHROPIC_CUSTOM_HEADERSapiKeyHelper
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.

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

See this entry in the whole of v2.1.227 →