403 Forbidden message when calling the v3 Google Calendar API using a Service Account via OAuth 2.0

Question

This is a follow on from my thread about a 401 error when using the Google Calendar API and OAuth2, which can be found here

This contains details of the account setup that leads onto my next question, so I wont repeat myself in this thread.

OK, so when when I call the following code to update a Calendar event I get a 403 forbidden error.

for (Event event : events.getItems())
{
    event.setSummary("XXX" + event.getSummary());

    Event updatedEvent = calendar.events().update(CALENDAR_ID, event.getId(), event).execute();
}

Here is the returned error message:

com.google.api.client.googleapis.json.GoogleJsonResponseException: 403 Forbidden
{
    "code" : 403,
    "errors" : [ {
        "message" : "Forbidden"
     } ],
    "message" : "Forbidden"
}

What have I tried? Well, I have re-read the (rather poor) Google documentation about Service Accounts, re-checked my API Console account settings, tried changing the code that builds the credential (this leads to other errors so is a regression on my previous thread).

In short, nothing works, so is there anything obvious I am missing?

Answer 1

In my case I had to enable the CalDAV API in the Google API console. It gives a 403 response if disabled.

I know this is an old question, but this might be helpful for someone.