TypeError: Failed to fetch

{
  "manifest": {
    "error": "TypeError: Failed to fetch",
    "id": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/131/manifest",
    "isFetching": false
  },
  "window": {
    "autoScrollAnnotationList": true,
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-a0f74c84-e5c3-4200-b9b2-63d304f7c047",
      "cw-07a4778b-3188-4844-bb4e-126afd76cffe"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-a9d92675-2580-4529-8868-6f7e540ce349",
    "manifestId": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/131/manifest",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-07a4778b-3188-4844-bb4e-126afd76cffe",
    "loadedManifest": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/131/manifest"
  }
}