TypeError: Failed to fetch

{
  "manifest": {
    "error": "TypeError: Failed to fetch",
    "id": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/441/manifest",
    "isFetching": false
  },
  "window": {
    "autoScrollAnnotationList": true,
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-db071cd6-e96b-476a-bf49-82058586e80c",
      "cw-2f66a54f-c2af-4461-99cc-484132852883"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-be48e9c8-d152-4772-951c-014f758865d5",
    "manifestId": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/441/manifest",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-2f66a54f-c2af-4461-99cc-484132852883",
    "loadedManifest": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/441/manifest"
  }
}