TypeError: Failed to fetch

{
  "manifest": {
    "error": "TypeError: Failed to fetch",
    "id": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/554/manifest",
    "isFetching": false
  },
  "window": {
    "autoScrollAnnotationList": true,
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-dfc840a5-3a43-4ee1-a8f5-684606b73998",
      "cw-de4bad5c-3d01-49a3-9699-66807dc7e433"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-eb8297bf-82f0-4c6a-88ba-87d450b42a56",
    "manifestId": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/554/manifest",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-de4bad5c-3d01-49a3-9699-66807dc7e433",
    "loadedManifest": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/554/manifest"
  }
}