TypeError: Failed to fetch

{
  "manifest": {
    "error": "TypeError: Failed to fetch",
    "id": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/851/manifest",
    "isFetching": false
  },
  "window": {
    "autoScrollAnnotationList": true,
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-b7a508e1-33dd-4491-a554-acdd11099da2",
      "cw-5b90fa6f-8073-4239-b114-e724ec4c55ef"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-0b5a64ca-6a8c-4007-96c3-20ed33fdc539",
    "manifestId": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/851/manifest",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-5b90fa6f-8073-4239-b114-e724ec4c55ef",
    "loadedManifest": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/851/manifest"
  }
}