UNAUTHENTICATED
GCP UNAUTHENTICATED means the request does not include valid authentication credentials for the requested Google Cloud API operation.
Last reviewed: February 12, 2026|Editorial standard: source-backed technical guidance
What Does Unauthenticated Mean?
Identity verification fails before authorization is evaluated, so requests are rejected immediately and downstream API workflows cannot start.
Common Causes
- -Access token, ID token, or signed credential is missing, expired, or malformed.
- -Token audience, issuer, or scope does not match the target API endpoint.
- -Application Default Credentials resolve from the wrong source for the running environment.
- -Workload Identity Federation or service-account impersonation is configured incorrectly.
- -Proxy, gateway, or middleware strips `Authorization` headers in transit.
How to Fix Unauthenticated
- 1Inspect active credential source and token claims (`aud`, `iss`, `exp`) in runtime before rotating secrets.
- 2Refresh or reacquire credentials using the correct ADC flow for that environment.
- 3Verify target API scopes/audience and service-account impersonation chain end to end.
- 4Trace request headers through ingress and proxy hops to ensure auth metadata is preserved.
Step-by-Step Diagnosis for Unauthenticated
- 1Capture the failing request with timestamp, endpoint, principal identity, and token type.
- 2Decode token claims and compare against API expectations for audience and issuer.
- 3Verify ADC resolution order and identity source used by the workload at runtime.
- 4Check clock drift and retry with a known-good credential path to isolate environment-specific auth failures.
Credential Source and Token Claim Validation
- -Confirm ADC is loading the intended credential file or metadata identity (example: local user ADC file mounted into production container unexpectedly).
- -Inspect token claims for endpoint compatibility (example: ID token minted for Cloud Run URL used against a Google API expecting OAuth access token).
Federation and Transport Integrity
- -Audit Workload Identity Federation or impersonation steps for trust and principal mapping issues (example: pool provider subject mismatch blocks token exchange).
- -Trace auth headers across proxies and service mesh layers (example: ingress policy drops `Authorization` on internal redirect).
How to Verify the Fix
- -Replay the exact failing request and confirm UNAUTHENTICATED is no longer returned.
- -Verify tokens refresh correctly across at least one full credential lifetime window.
- -Check logs for sustained absence of credential-validation failures after rollout.
How to Prevent Recurrence
- -Standardize credential acquisition through shared auth libraries and environment-specific ADC policy.
- -Monitor token-expiry skew, metadata-server reachability, and impersonation error rates.
- -Add pre-deploy auth smoke tests that validate audience and scope against critical APIs.
Pro Tip
- -log hashed token claim fingerprints (`iss/aud/sub`) at auth boundaries to detect silent credential-source drift before outages.
Decision Support
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Playbook
Auth Incident Playbook (401 / UNAUTHENTICATED)
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Official References
Provider Context
This guidance is specific to GCP services. Always validate implementation details against official provider documentation before deploying to production.