Mirador - viewer

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

{
  "manifest": {
    "error": "SyntaxError: Unexpected token '<', \"<!DOCTYPE \"... is not valid JSON",
    "id": "/api/digital_items/132112/2/manifest.json/",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-c210a9ba-d690-4ca6-a5dd-cd8d0d6b9e26",
      "cw-66b506bc-2500-4770-bdbc-253127429aaf"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-68b7662d-bbd1-481e-ad0a-6042923573e6",
    "manifestId": "/api/digital_items/132112/2/manifest.json/",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "annotations",
    "thumbnailNavigationId": "cw-66b506bc-2500-4770-bdbc-253127429aaf",
    "thumbnailNavigationPosition": "off",
    "loadedManifest": "/api/digital_items/132112/2/manifest.json/",
    "canvasIndex": 0
  }
}