Amazon s3 .Net core 3.1从S3下载文件

我有下面这个下载文件的方法

    public async Task<GetObjectResponse> DownloadFile(string bucket, string filePath)
    {
        var client = Client();
        GetObjectRequest req = new GetObjectRequest
        {
            BucketName = bucket,
            Key = filePath
        };
        return await client.GetObjectAsync(req);
    }

我在var下载变量上遇到以下错误：

download.ResposeSTream.ReadTimeOut（），download.ResposeSTream.WriteTimeOut（），download.ResposeSTream.Length，download.ResposeSTream.Position 引发了异常System.InvalidOperationException和

        var download = await _s3Service.DownloadFile(Constants.S3.BUCKET, attachment.Location);
        MemoryStream stream = new MemoryStream();
        await download.ResponseStream.CopyToAsync(stream);