UNAUTHENTICATED
GCP UNAUTHENTICATED means the request does not include valid authentication credentials for the requested Google Cloud API operation.
Last reviewed: February 3, 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
Authorizationheaders 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
Authorizationon 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
Compare Guide
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Playbook
Auth Incident Playbook (401 / UNAUTHENTICATED)
Use this playbook to separate missing, expired, or invalid identity proof from authorization and transport failures, and apply credential-source-correct fixes safely.
Playbook
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Use this playbook to separate browser-enforced cross-origin policy failures from server-side CORS header and route defects and apply strict origin and credential controls safely.
Official References
Provider Context
This guidance is specific to GCP services. Always validate implementation details against official provider documentation before deploying to production.