Gmail / Google Drive verification error 400 in Make.com

Updated 2026-08-01

Connecting Gmail or Google Drive to Make.com fails with a verification or error 400. That usually blocks the OAuth consent step — before any module mapping matters. This page separates connection setup problems from later scenario errors.

What is failing

Google can refuse the OAuth screen when the app is in testing, the redirect URI does not match, the consent screen is incomplete, or the Google Cloud project is misconfigured for the scopes Make requests.

A 400 at connect time is not the same as BundleValidationError later in a run. Fix the connection first; only then debug Sheets or Gmail modules.

What to check

Confirm you are using Make's standard Google connection unless you intentionally built a custom OAuth client — custom clients need a correct consent screen and authorized redirect URIs.

If Google shows an unverified app warning, that is expected for many personal projects in testing mode; adding test users in Google Cloud is often required.

When the error text is long, paste it into the free diagnosis. Connection and OAuth docs are where Make's Help Center helps most; invented "fix scopes" tips from generic AI often miss the exact Google Cloud step.

Paste the error for a sourced diagnosis

If you still have the execution log, use the free tool — Make's docs only, every claim linked, or an honest refusal when coverage is missing.

Diagnose this error free →

Example you can try: Gmail connection fails with verification error 400 when I try to authorize Google in Make.

Official Make documentation

FAQ

Does this mean my scenario blueprint is wrong?

Not yet. If authorization never completes, the scenario never gets a valid connection. Finish OAuth before editing filters or mappings.

Is this related to InvalidAccessTokenError later?

Same family (access), different moment. Verification 400 is usually at connect time; InvalidAccessTokenError often appears after a token expires or is revoked.

Related guides

Eviverse is independent and not affiliated with Make. These guides are original explanations with links to Make's public Help Center — not republished documentation.