> For the complete documentation index, see [llms.txt](https://docs.n8n.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.n8n.io/integrations/builtin/trigger-nodes/n8n-nodes-base.gmailtrigger/common-issues.md).

# Common issues

Here are some common errors and issues with the [Gmail Trigger node](/integrations/builtin/trigger-nodes/n8n-nodes-base.gmailtrigger.md) and steps to resolve or troubleshoot them.

## 401 unauthorized error <a href="#id-401-unauthorized-error" id="id-401-unauthorized-error"></a>

The full text of the error looks like this:

```
401 - {"error":"unauthorized_client","error_description":"Client is unauthorized to retrieve access tokens using this method, or client not authorized for any of the scopes requested."}
```

This error occurs when there's an issue with the credential you're using and its scopes or permissions.

To resolve:

1. For [OAuth2](/integrations/builtin/credentials/google/oauth-single-service.md) credentials, make sure you've enabled the Gmail API in **APIs & Services > Library**. Refer to [Google OAuth2 Single Service - Enable APIs](/integrations/builtin/credentials/google/oauth-single-service.md#enable-apis) for more information.
2. For [Service Account](/integrations/builtin/credentials/google/service-account.md) credentials:
   1. [Enable domain-wide delegation](/integrations/builtin/credentials/google/service-account.md#enable-domain-wide-delegation).
   2. Make sure you add the Gmail API as part of the domain-wide delegation configuration.