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Google OAuth Setup on n8n

2 min read

Fix: “Access blocked – has not completed the Google verification process” #

When you try to connect Google (Gmail / Google Drive) inside n8n, you may see this error:

“Access blocked: <your-domain> has not completed the Google verification process.”

This message comes from Google, not from n8n or SNBD Host. It means the Google app you are using is not verified for public use. For security, Google blocks the login. The easiest way to solve this is to create your own Google Cloud project and OAuth keys, and then use those keys in n8n. When you use your own project and add your email as a test user, Google allows the login and the error goes away.

What you will do #

  1. Create a project in Google Cloud.
  2. Turn on the Gmail API.
  3. Set up the OAuth consent screen and add your Google email as a Test user.
  4. Create OAuth Client ID (Client ID + Client Secret).
  5. Paste these details into n8n and connect your Google account.

Part 1 – Set up Google Cloud #

1) Create a Google Cloud project #

  1. Go to Google Cloud Console.
  2. At the top, click the project picker → New Project.
  3. Give it a name, for example: “n8n Gmail Key”.
  4. Click Create.

2) Turn on the Gmail API #

  1. In the left menu, open APIs & Services → Library.
  2. Search for “Gmail API”.
  3. Click it and then click Enable.

3) Set up the OAuth consent screen #

  1. Go to APIs & Services → OAuth consent screen.
  2. User type: choose External → Create.
  3. Fill in:
    • App name: e.g. “My n8n Automations”.
    • User support email: your Google email.
    • Developer contact info: your email again.
  4. Click Save and Continue through the next screens. You can keep the default settings.
  5. On the Test users step, click + Add users and add the Google email(s) you will use in n8n.
  6. Click Save and Continue → Back to Dashboard.

Important: If the email you use in n8n is not added here as a Test user, you will keep seeing “Access blocked” or similar errors.

4) Prepare to create OAuth client #

  1. Go to APIs & Services → Credentials.
  2. Click + Create credentials → OAuth client ID.
  3. Application type: choose Web application.
  4. Name: e.g. “n8n Web Client”.
  5. Stop here for a moment – we need the Redirect URL from n8n before finishing.

Part 2 – Connect with n8n #

5) Get Redirect URL from n8n #

  1. Open your n8n instance.
  2. Go to Credentials.
  3. Click New Credential and search for “Gmail”.
  4. Select Google OAuth2 API (Gmail).
  5. Copy the Redirect URL shown in the form. It will look like your n8n domain.

6) Finish OAuth client in Google Cloud #

  1. Go back to the OAuth client creation screen in Google Cloud.
  2. Under Authorized redirect URIs, click + Add URI.
  3. Paste the Redirect URL you copied from n8n.
  4. Click Create.
  5. Google will now show your Client ID and Client Secret.
    Copy and save them safely.

7) Connect in n8n #

  1. Return to n8n → your Gmail credential.
  2. Paste the Client ID and Client Secret into the fields.
  3. Click Save, then click Connect my account.
  4. Sign in with the same Google email you added as a Test user.
  5. If you see a warning like “This app isn’t verified”, click:
    Advanced → Go to <App name> (unsafe) → then Continue.
  6. Accept the permissions. The window will close and the credential in n8n should show as connected.

Why the “Access blocked” error happens #

  • The Google app (OAuth client) is not verified for public use.
  • The email you used to sign in is not added as a Test user on the OAuth consent screen.
  • The required API (for example Gmail API) is not enabled in your project.
  • The Redirect URL in Google Cloud does not match the Redirect URL from n8n.

By following the steps above, you create your own small private Google app and tell Google: “Only I (and the emails I added as test users) will use this.” For this private usage, Google allows the connection even though the app is not fully verified for the public.