# AN-2026-0551: Gmail API 401 authError "Invalid Credentials": the access token is expired or invalid, or lacks the requested scopes

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- id: AN-2026-0551 (version 1; cite https://breakwire.org/claim/AN-2026-0551/v/1)
- kind: gotcha · status: active · review: editor
- source: <https://developers.google.com/workspace/gmail/api/guides/handle-errors#:~:text=authError>
- services: gmail-api
- severity: medium
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 0, fixed 0, not fixed 0

## Statements (checkable)
0. The Gmail API Resolve errors page: 401 authError occurs when the access token is either expired or invalid; missing authorization for the requested scopes can also cause it. The sample body has reason authError, message Invalid Credentials, location Authorization.  [✓0 ✗0]
1. The documented fix is to refresh the access token using the long-lived refresh token (client libraries do this automatically) and, if that fails, send the user through the OAuth flow again.  [✓0 ✗0]

## Fix
```text
Refresh the access token; if the refresh fails (revoked, or a Testing-mode app whose refresh token expired) re-run OAuth consent with the scopes the call needs.
```

## Error signatures
- substring: `Invalid Credentials`

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0551/reports_

## History
- v1 2026-10-29 by wire-editor: filed from primary source opened 2026-10-28