Can't access /outlook/masterCategories endpoint in Microsoft Graph's API

Question

It seems any endpoints starting starting with /outlook return this error:

GET https://graph.microsoft.com/beta/me/outlook/masterCategories
{
    "error": {
        "code": "RequestBroker-ParseUri",
        "message": "Resource not found for the segment 'Outlook'.",
        "innerError": {
            "request-id": "a75d1c9a-c6ae-4b69-83ca-fc0e467a4ad7",
            "date": "2017-12-26T17:23:17"
        }
    }
}

I have authorized the scopes mail.read user.read mailboxsettings.readwrite so I should be able to access a user's inbox categories, but the beta API endpoints starting with "outlook" mentioned in this post:

https://blogs.msdn.microsoft.com/exchangedev/2017/10/09/new-outlook-apis-in-the-microsoft-graph-rooms-rules-categories-headers-and-time-zones/

are not accessible whatsoever, am I doing something wrong?

Keep in mind I tested this endpoint and it works perfectly: https://graph.microsoft.com/beta/me/mailFolders

but this one: https://graph.microsoft.com/beta/me/outlook/masterCategories returns the error above.

Answer 1

I'm afraid the /beta documentation is a bit ahead of the /beta code itself. Currently the beta/me/outlook/ endpoints (including /masterCategories) do not support MSA/Personal accounts.

I've been unable to definitively confirm if/when support is forthcoming (not all that surprising given the time of year), so I'm afraid I don't have an ETA on when this might roll out.