TypeError: Failed to fetch

{
  "manifest": {
    "error": "TypeError: Failed to fetch",
    "id": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/496/manifest",
    "isFetching": false
  },
  "window": {
    "autoScrollAnnotationList": true,
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-e1724be3-131e-46ea-8688-8e4cad5c84d9",
      "cw-f6704bc3-d2bf-4bed-a2a6-aeaed6cdc630"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-170be087-e278-4fc5-bbd9-955de3e66e44",
    "manifestId": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/496/manifest",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-f6704bc3-d2bf-4bed-a2a6-aeaed6cdc630",
    "loadedManifest": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/496/manifest"
  }
}