原因在于iis不支持.json扩展名，官方教程地址https://ckeditor.com/docs/ckfinder/ckfinder3-php/quickstart.html#quickstart_troubleshooting_json
You will thus need to add JSON as a new MIME type in your IIS configuration.
Set the following options in the Add MIME Type dialog:
- File name extension: .json.
- MIME type: application/json.