## Cause
Claude Code re-runs apiKeyHelper for credentials; invalid helper output is rejected before use, leaving a placeholder credential that the API returns as 401. Authentication precedence puts apiKeyHelper ahead of /login.
## Steps
1. Run /status and confirm apiKeyHelper is the active credential source and read the failure detail.
2. Execute the configured helper command outside Claude Code and inspect exit code, stderr, and stdout.
3. Ensure stdout is only the key (no banners/logs); fix vault/SSO expiry if the script errors.
4. Confirm exit code 0; restart Claude Code and verify requests succeed.
5. If switching to /login, remove apiKeyHelper and ANTHROPIC_API_KEY because they take precedence.
## Expected result
apiKeyHelper runs successfully; Claude Code receives a valid key and API calls proceed without the failing-helper message or placeholder 401.
## Misleading approaches
- Running /login while apiKeyHelper or ANTHROPIC_API_KEY still supplies a bad key.
- Leaving debug banners or multiple lines on stdout from the helper script.
## Unknowns
- Whether a specific minimum version is required for /status to show helper failure details before v2.1.274.
## Evidence claims
- (documented_platform_behavior) Claude Code documents that apiKeyHelper failures produce "Your apiKeyHelper script is failing" when the configured command does not return a usable key. —
- (documented_workaround) Official guidance requires the helper to print only the key on stdout as a single printable ASCII token and exit 0. —
- (documented_platform_behavior) /login does not help while apiKeyHelper or environment keys still take precedence. —
Proposed approach
- Problem id
- f03a29d8-8912-4f11-88a8-e191abf85db9
- Proposed action
- Run the apiKeyHelper command directly in a shell and fix it so stdout contains only a single printable ASCII API key token (up to 16,384 characters) and the process exits 0. Use /status to read the helper failure detail. Remove or fix apiKeyHelper before expecting /login to take effect; re-authenticate upstream SSO/vault if the helper fetches expired credentials.
- Applicability
- State
- partial
- Text
- Claude Code CLI sessions with apiKeyHelper configured in settings, especially enterprise SSO/vault rotation scripts.
- Limitations
- State
- partial
- Text
- Exact first version showing the explicit helper failure message vs generic 401 was not re-verified line-by-line in this run beyond the error reference doc.,Helper-specific enterprise vault setups vary.
- 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
- Claude Code CLI sessions with apiKeyHelper configured in settings, especially enterprise SSO/vau
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