Gmail API: Unable to access inbox - Insufficient token scope error

Other Questions Gmail
1

I’m stuck trying to read my Gmail inbox using the API. I’ve successfully listed labels and sent emails, but can’t fetch messages.

Here’s the error I’m getting:

{
  "code": 403,
  "message": "Request had insufficient authentication scopes.",
  "status": "PERMISSION_DENIED"
}

My code uses GmailScopes.MAIL_GOOGLE_COM for authentication. I’ve tried:

  • Using specific scopes (readonly, modify, etc.)
  • Rechecking GCP settings
  • Clearing stored credentials
  • Revoking and re-authorizing the app
  • Downloading fresh credentials

Nothing worked. The API still blocks GET requests for messages.

My main class is pretty standard - it sets up auth, builds the service, and tries to list messages:

public class EmailReader {
  // ... auth setup ...
  
  public static void main(String[] args) throws Exception {
    GmailService service = buildService();
    service.users().messages().list("me").execute(); // Fails here
    EmailUtils.printMessages(service);
  }
}

Any ideas what I’m missing? I’m out of troubleshooting options!

2

hey man, i had this same problem last week. turns out i needed to use the specific scope for reading messages - ‘https://www.googleapis.com/auth/gmail.readonly’. make sure you update both your code and the oauth consent screen in google cloud console. also, delete your old credentials completely and reauthenticate. that should fix it

3

I ran into a similar issue when working with the Gmail API recently. The key was making sure I had the correct scopes configured both in my code and in the Google Cloud Console.

For reading inbox messages, you’ll want to use the ‘https://www.googleapis.com/auth/gmail.readonly’ scope instead of ‘GmailScopes.MAIL_GOOGLE_COM’. The latter is too broad and might be causing the permission issues.

Also, double-check your OAuth consent screen in the Google Cloud Console. Make sure the scopes you’re requesting in your code are also listed there. Sometimes, there’s a mismatch that can cause these errors.

Lastly, if you’ve made changes to scopes, you might need to delete the stored credentials completely (not just clearing them) and go through the OAuth flow again. The token you’re using might still have the old scopes associated with it.

Hope this helps! Let me know if you need any clarification on these steps.

4

I encountered a similar issue and found that the problem often lies in the OAuth 2.0 Client ID settings. Make sure you’ve created a proper OAuth 2.0 Client ID in the Google Cloud Console for your application type (desktop, web, etc.). Then, download the client configuration and use it in your code.

Also, when requesting scopes, be explicit. Instead of using GmailScopes.MAIL_GOOGLE_COM, try GmailScopes.GMAIL_READONLY or GmailScopes.GMAIL_MODIFY, depending on your needs. This more granular approach often resolves permission issues.

If you’re still having trouble, check the API’s enabled services in your Google Cloud project. Sometimes, the Gmail API gets disabled unexpectedly. Re-enabling it might solve your problem.

Lastly, ensure your GCP project is properly configured with a valid OAuth consent screen, including your app’s name, logo, and authorized domains.