TypeError: Failed to fetch

{
  "manifest": {
    "error": "TypeError: Failed to fetch",
    "id": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/123/manifest",
    "isFetching": false
  },
  "window": {
    "autoScrollAnnotationList": true,
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-1261d3d3-176e-44f2-a115-7ceb14d974e5",
      "cw-048a1cbd-3064-4669-9b9c-47384a9c2b08"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-bbf98889-04ee-409d-8cb2-cd4678be6e3b",
    "manifestId": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/123/manifest",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": false,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-048a1cbd-3064-4669-9b9c-47384a9c2b08",
    "loadedManifest": "http://jaegerstaetter-test.literaturtirol.at/omekas/iiif/2/123/manifest"
  }
}