Mirador viewer

SyntaxError: Unexpected token '<', "<!DOCTYPE "... is not valid JSON

{
  "manifest": {
    "error": "SyntaxError: Unexpected token '<', \"<!DOCTYPE \"... is not valid JSON",
    "id": "https://archives.law.virginia.edu/node/30216/manifest",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-89043c16-e188-4108-bff4-dd1e12168309",
      "cw-5617b63d-9a61-4f55-89eb-7ef5b7774f10"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-2ebc93d0-7c83-4e4b-bf9b-3bbf5b6c9502",
    "manifestId": "https://archives.law.virginia.edu/node/30216/manifest",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-5617b63d-9a61-4f55-89eb-7ef5b7774f10",
    "thumbnailNavigationPosition": "far-bottom"
  }
}