## Support semantics
This is a **candidate / unverified** Solution from the KFA Solution Factory Tier-2 gate. It is source-grounded research material, not an Outcome, and does **not** claim independent reproduction or confirmed field success.
## Cause
API rejects the key, or Claude Code blocks ANTHROPIC_API_KEY containing characters HTTP headers cannot carry before the request is sent.
## Steps
1. Run env | grep ANTHROPIC in the same terminal that launches claude.
2. If the message cites a character position, re-type the key without line breaks or invisible characters.
3. Confirm the key is active in the Anthropic Console; rotate if revoked.
4. Unset ANTHROPIC_API_KEY and run /login to use subscription credentials if desired.
5. Run /status to see which credential is active.
## Expected result
Requests authenticate; Invalid API key and pre-send header validation errors stop.
## Misleading approaches
- Assuming /login credentials are used while ANTHROPIC_API_KEY remains set in the environment.
## Limitations
- apiKeyHelper failures use a different error path per docs.
- Not reproduced in this factory lane.
## Unknowns
- Which dotenv/direnv layer loaded a stale key in a given IDE setup.
## Evidence claims
- (documented_platform_behavior) Invalid API key means the API rejected ANTHROPIC_API_KEY or apiKeyHelper output, or Claude Code blocked the env key before send. — https://code.claude.com/docs/en/errors
- (documented_platform_behavior) Stale keys from direnv/dotenv/IDE .env loading are a documented cause; env | grep ANTHROPIC is the recommended check. — https://code.claude.com/docs/en/errors
Proposed approach
- Problem id
- ac1309fa-f3b2-40e6-b567-5cbf65437694
- Proposed action
- In the same shell run env | grep ANTHROPIC; fix or re-type the key (especially around reported character positions); unset ANTHROPIC_API_KEY and /login if using subscription auth; verify /status.
- Applicability
- State
- partial
- Text
- support: candidate_unverified (not an Outcome; no reproduction claim); Claude Code CLI when ANTHROPIC_API_KEY is set via shell, direnv, IDE terminal, or .env tooling; includes stale/revoked keys and keys with line breaks or other header-invalid characters.; fix_status: CONFIRMED_SOLUTION
- Limitations
- State
- partial
- Text
- apiKeyHelper failures use a different error path per docs. Not reproduced in this factory lane.
- Success criteria
- Not supplied
- Risk notes
- Not supplied
- Lifecycle
- active
Needs revalidation
LOW EVIDENCE
This exact knowledge revision needs ordinary execution evidence.
Useful environment or version
- State
- partial
- Text
- support: candidate_unverified (not an Outcome; no reproduction claim); Claude Code CLI when ANTH
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