Gmail Trigger Error: Cannot read properties of undefined (reading 'includes') in n8n Cloud Workflow

Based on the error and behavior you’re describing, it appears that the Gmail Trigger isn’t receiving the expected data from Gmail. Here are a few steps to help troubleshoot and resolve the issue:

1. Check Your Credentials

• OAuth2 Credentials:
  Ensure that you’ve enabled the Gmail API in your Google Cloud project. Double-check the scopes requested by your credentials. An incorrectly configured OAuth2 credential (or one that’s missing the proper scopes) might cause Gmail’s response not to include expected fields.

• Service Account Credentials:
  If you’re using a service account, verify that you’ve enabled domain-wide delegation and added the Gmail API to your delegation configuration. Otherwise, the response might be different from what the node expects, causing JavaScript errors.

See the documentation on Google OAuth2 Single Service - Enable APIs and Google Service Account: Finish your n8n credential for additional details.

2. Verify Gmail API Response

Since the error states that it “Cannot read properties of undefined (reading 'includes')”, it suggests that the node expects a property (likely from the API response) that isn’t present. This can happen if:

• The API response format has changed,
• The API isn’t returning data because of a credential/scope issue, or
• A transient issue with Gmail’s API response.

Testing your credentials with a simple “Get” operation (or using a separate Gmail API test tool) might help confirm that Gmail is returning the proper structure.

3. Check for Node or Library Updates

If nothing appears misconfigured on your side, it’s possible that a recent change in the Gmail API response has affected the node’s behavior. In that case:

• Look for any available updates for your n8n version or the Gmail node.
• Check the n8n community forums for any recent posts about similar issues. For example, the thread you mentioned from a few years ago indicated that changes in the remote service response might affect proper functioning.

Next Steps

• Revalidate your credentials configuration: Double-check that you have the correct scope and that the Gmail API is enabled.
• Test API calls externally: Use tools like the APIs Explorer to see if the data structure matches what you expect.
• Review n8n updates or community posts: It may also help to see if similar issues have been reported recently in the n8n community.

Following these steps should help pinpoint whether the issue lies with your credentials/configuration or a change in the Gmail API’s response. Let us know if you need further assistance!