The message means that your access-token did expire, n8n tried to refresh it but it did fail because on OAuth authentication no refresh-token got returned. For that reason is it now missing and can so not request a new access-token, as to do so it requires that refresh-token.
That happens because Google somehow does return a refresh-token only for the very first authentication request by default. Guess you authenticated maybe multiple times.
The solution is to tell Google to always return a refresh-token. That can be done if you set in your Google OAuth2 credentials the parameter “Auth URI Query Parameters” to “access_type=offline&prompt=consent”. Once you did that and then connect again, it should do two things:
- Give you a new access-token that the requests are possible again
- This time also return a refresh-token so that it also keeps on working once the access-token expired
Hope that helps!