Why Is Gmail OAuth2 API Not Providing a Redirection URL During Credential Setup?

It sounds like n8n isn’t showing the OAuth redirect URL as expected. When configuring Google OAuth2 in n8n, the redirect URL is generated based on your instance’s public URL configuration. Here are a few things to double-check:

1. Webhook Base URL / Public URL:
   Make sure your n8n instance is configured with a proper public URL. If n8n can’t determine its external address, it won’t be able to generate the correct redirect URL that you need to paste into Google Cloud’s Authorized Redirect URIs list.

   • For self-hosted instances, check that you’ve set the environment variable (like WEBHOOK_URL or similar) correctly.

2. Credential Type and Setup:
   Ensure you are using the correct OAuth2 credential type for Google. In your credential setup, after creating your Google OAuth client in the Cloud Console, you should be able to copy the OAuth Redirect URL from the credential configuration in n8n. If that step isn’t showing up, it might indicate that the wrong credential type is selected or the configuration wasn’t saved correctly.

3. Instance Mode (Cloud or Self-Hosted):
   If you’re using n8n.cloud versus a self-hosted version, the way the URL is generated might differ. On n8n.cloud the URL is preset whereas self-hosted setups require explicit configuration of the public URL.

Review your n8n instance settings and ensure that your environment variables for the public webhook URL are correctly set. Once n8n knows its public URL, it should display the redirection URL in the credentials view, which you can then paste into Google Cloud.

If the problem persists, check your n8n logs for any errors related to credential generation or webhook configuration. This can often highlight misconfigurations that prevent the correct URL from being generated.

Hope this helps clear things up!