Subject and Courses lists broken

The following error appears as response to the courses/subjects query:

  {
    "errors": [
      {
        "message": "ContentType matching query does not exist.",
        "locations": [
          {
            "line": 2,
            "column": 3
          }
        ],
        "path": [
          "items"
        ]
      }
    ],
    "data": {
      "items": null
    }