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/28101/manifest",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-30d14f49-afe2-465d-9b44-5ecbed2784de",
      "cw-1db8d8ad-6896-4476-8747-6b97b68a33b3"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-31a9c277-ad6c-4d2a-b0f6-be776c866937",
    "manifestId": "https://archives.law.virginia.edu/node/28101/manifest",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-1db8d8ad-6896-4476-8747-6b97b68a33b3",
    "thumbnailNavigationPosition": "far-bottom"
  }
}