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_12P_01426/manifest.json",
    "isFetching": false
  },
  "window": {
    "collectionIndex": 0,
    "companionAreaOpen": true,
    "companionWindowIds": [
      "cw-79cf9fcf-54b9-4ca6-bf64-4838fec323c9",
      "cw-2d81bf01-7392-4416-8631-ed9f47b1a736"
    ],
    "draggingEnabled": true,
    "highlightAllAnnotations": false,
    "id": "window-ddc7359a-00c1-49a8-be78-b4d7d2a94c04",
    "manifestId": "https://iiif.participatory-archives.ch/SGV_12P_01426/manifest.json",
    "maximized": false,
    "rangeId": null,
    "rotation": null,
    "selectedAnnotations": {},
    "sideBarOpen": true,
    "sideBarPanel": "info",
    "thumbnailNavigationId": "cw-2d81bf01-7392-4416-8631-ed9f47b1a736",
    "loadedManifest": "https://iiif.participatory-archives.ch/SGV_12P_01426/manifest.json"
  }
}