Google OAuth: Error 403: access_denied, app is in testing
The OAuth consent screen is in Testing mode, which only allows the accounts explicitly listed as test users. Refresh tokens issued in that mode also expire after seven days, so an integration that worked all week fails on the eighth day.
Quick fix
Read the commands before running them. Anything that restarts a service, deletes data or changes permissions should be tried on a non-production system first.
# Google Cloud console: APIs and Services > OAuth consent screen
# 1. Add the account under Test users, or
# 2. Publish the app (Publishing status: In production)
# Sensitive or restricted scopes need verification before publishing.
# Internal apps in a Workspace organisation can use User type: Internal
# and skip verification entirely.
# Server to server integrations should not use this flow at all:
gcloud iam service-accounts keys create key.json \
[email protected]
# then use domain wide delegation or workload identity federationHow to diagnose Auth errors
Identity errors are almost always configuration mismatches between two systems rather than code bugs: a redirect URI registered with a trailing slash, a client secret that was rotated on one side only, a clock that has drifted past the token skew allowance. Because the identity provider deliberately returns vague errors to avoid leaking information to attackers, the provider's own log is usually far more informative than the message your application receives.
If the quick fix above does not resolve it, work through these steps. They apply to this whole class of error, not just to this one message, which is usually what saves the time.
- Open the identity provider's log or event stream first. Auth0, Okta and Keycloak all record a detailed reason that they never send back to the client.
- Compare the redirect URI byte for byte, including scheme, port and trailing slash.
http://localhost:3000/callbackandhttp://localhost:3000/callback/are different URIs. - Decode the token rather than guessing. Paste it into a local JWT decoder and check
iss,aud,expandnbf, never a remote paste site, because tokens are credentials. - Check clock skew with
timedatectlorntpq -p. Kerberos, SAML and JWT all reject tokens outside a tight time window, and a drifting VM clock produces intermittent, unreproducible auth failures. - For passkeys and WebAuthn, verify the Relying Party ID matches the origin exactly and that the page is served over HTTPS or on
localhost. Nothing else is a secure context.
Tools worth reaching for
Provider audit logsjwt decoding (locally)openssl x509 -noout -textbrowser devtools network tab
Authoritative references
Primary documentation for this error, worth reading before applying any fix in production.
Related Auth errors
- Auth0: Callback URL mismatchAuth0 rejected the login because the redirect URL in the request is not in the application's…
- JWT: token used before issued / not valid yetValidation compared the token's iat or nbf claim against the verifier's clock and decided the…
- Keycloak: Invalid parameter: redirect_uriKeycloak rejected the redirect URI because it is not listed in the client's Valid Redirect…
- MFA: challenge timeout / code expiredA TOTP or push challenge was rejected because it expired or the device clock drifted outside…
- Microsoft Entra ID: AADSTS50011 (redirect URI mismatch)The redirect_uri sent in the authorisation request is not registered on the app registration…
- OAuth 2: invalid_grant (PKCE code_verifier does not match)The code_verifier sent to the token endpoint does not hash to the code_challenge sent to the…
- OIDC: nonce mismatchThe nonce in the returned ID token does not match the nonce sent in the auth request…
- OIDC: unable to find a signing key that matches the kidThe token was signed with a key the verifier does not have. Identity providers rotate signing…
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Something missing or wrong?
This entry is maintained by hand. If the fix is out of date, incomplete, or you have a better one, email a correction and it will be reviewed.