TypeError: Failed to fetch

{
  "manifest": {
    "error": "TypeError: Failed to fetch",
    "id": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/611/manifest",
    "isFetching": false
  },
  "window": {
    "autoScrollAnnotationList": true,
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-57220889-0e87-4003-b5bb-d08215966d66",
      "cw-c4c2c2dd-0a7f-4160-9005-f720a24a83e9"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-9dc54bce-757a-4027-92ab-f9fe73f07b96",
    "manifestId": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/611/manifest",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-c4c2c2dd-0a7f-4160-9005-f720a24a83e9",
    "loadedManifest": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/611/manifest"
  }
}