TypeError: Failed to fetch

{
  "manifest": {
    "error": "TypeError: Failed to fetch",
    "id": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/725/manifest",
    "isFetching": false
  },
  "window": {
    "autoScrollAnnotationList": true,
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-85b20580-dd76-49d1-bf65-647603cfce4a",
      "cw-586cd6ec-087e-45b7-89bf-e9bd91b559a5"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-e75d150d-a87c-4b33-b810-c5ba71cda113",
    "manifestId": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/725/manifest",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-586cd6ec-087e-45b7-89bf-e9bd91b559a5",
    "loadedManifest": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/725/manifest"
  }
}