Mirador viewer

SyntaxError: Unexpected token 'E', "Error from"... is not valid JSON

{
  "manifest": {
    "error": "SyntaxError: Unexpected token 'E', \"Error from\"... is not valid JSON",
    "id": "https://iiif.participatory-archives.ch/SGV_10P_00011/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-57e5e508-2842-4c51-82c6-20d85eec0fc4",
      "cw-15ad4691-2295-42b6-9c4e-9a8ca6071f9f"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-6f67be90-a8c2-42fd-b7f2-ea324f13b54e",
    "manifestId": "https://iiif.participatory-archives.ch/SGV_10P_00011/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": true,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-15ad4691-2295-42b6-9c4e-9a8ca6071f9f",
    "loadedManifest": "https://iiif.participatory-archives.ch/SGV_10P_00011/manifest.json"
  }
}