TypeError: Failed to fetch

{
  "manifest": {
    "error": "TypeError: Failed to fetch",
    "id": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/1634/manifest",
    "isFetching": false
  },
  "window": {
    "autoScrollAnnotationList": true,
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-4767e16b-1649-4f83-8857-8b6b0dc77aee",
      "cw-190d4dc9-4f49-4812-aef2-24731c3cb157"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-5da61450-9c59-4e5b-868c-eb779e57f9bd",
    "manifestId": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/1634/manifest",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-190d4dc9-4f49-4812-aef2-24731c3cb157",
    "loadedManifest": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/1634/manifest"
  }
}