TypeError: Failed to fetch

{
  "manifest": {
    "error": "TypeError: Failed to fetch",
    "id": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/368/manifest",
    "isFetching": false
  },
  "window": {
    "autoScrollAnnotationList": true,
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-d42be214-6652-41f4-8ac5-a7246049b18a",
      "cw-5da9f042-e185-49d8-8f85-4c40e4e3c119"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-d4a72995-a644-46a7-bdd0-2bfa9c815f5c",
    "manifestId": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/368/manifest",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-5da9f042-e185-49d8-8f85-4c40e4e3c119",
    "loadedManifest": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/368/manifest"
  }
}