TypeError: Failed to fetch

{
  "manifest": {
    "error": "TypeError: Failed to fetch",
    "id": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/835/manifest",
    "isFetching": false
  },
  "window": {
    "autoScrollAnnotationList": true,
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-88d5e356-63b9-43bc-a714-391fcfda48a6",
      "cw-6c153bbc-d5ec-45f1-b6d0-efe43f719c42"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-dab311ec-0817-4f72-9b66-78d56fc4afb6",
    "manifestId": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/835/manifest",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-6c153bbc-d5ec-45f1-b6d0-efe43f719c42",
    "loadedManifest": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/835/manifest"
  }
}