SharePoint User Profile REST API unknown error

Question

I activated user profiles (and managed metadata services), but when I call: http://<mysharepointsite>/_api/SP.UserProfiles.PeopleManager/GetMyProperties

I get:

<m:error xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata">
<m:code>-1, Microsoft.SharePoint.Client.UnknownError</m:code>
<m:message xml:lang="en-US">Unknown Error</m:message>
</m:error>

I can query lists just fine with REST. Do I need to activate something? Or does it take some time for this information to be query-able?

Do I need to create a site collection for Mysite?

EDIT Solved:

I needed to setup Mysite. Now everything works fine.

Answer 1

Setting up Mysite fixed the problem.

Answer 2

This code works fine against my Office 365 Tenant

$.ajax({
        url: appweburl + "/_api/SP.UserProfiles.PeopleManager/GetMyProperties",
        method: "GET",
        headers: {
                "Accept": "application/json; odata=verbose",
        }

})

Have you granted you app the permissions to User Profiles (Social)? (Although you should get access denied, not unknown error then..)