远程服务器返回错误（550）文件不可用（例如，找不到文件没有访问权限）

Question

远程服务器返回错误（550）文件不可用（例如找不到文件无法访问）。

当我下载两个文件时，一个是21个字节的Date.txt文件，另一个是2 GB .zip文件。 Zip文件下载成功，但是在下载Date.txt时出现错误：

我正在从FTP文件下载中尝试此代码。：

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    string[] files = ReadFileList();
    FTPSettings.IP = "xx.xx.xxx.xxx/TextureData";
    FTPSettings.UserID = "xxxx";
    FTPSettings.Password = "xxx";
    //FtpWebRequest reqFTP = null;
    //Stream ftpStream = null;
    foreach (string file in files)
    {
        //string fileName = e.Argument.ToString();
        FtpWebRequest request = (FtpWebRequest)WebRequest.Create("ftp://" + FTPSettings.IP + "/" + file);
        request.Credentials = new NetworkCredential(FTPSettings.UserID, FTPSettings.Password);
        request.Method = WebRequestMethods.Ftp.GetFileSize;
        request.Proxy = null;
        long fileSize; // this is the key for ReportProgress
        using (WebResponse resp = request.GetResponse())
            fileSize = resp.ContentLength;
        request = (FtpWebRequest)WebRequest.Create("ftp://" + FTPSettings.IP + "/" + file);
        request.Credentials = new NetworkCredential(FTPSettings.UserID, FTPSettings.Password);
        request.Method = WebRequestMethods.Ftp.DownloadFile;
        using (FtpWebResponse responseFileDownload = (FtpWebResponse)request.GetResponse())
        using (Stream responseStream = responseFileDownload.GetResponseStream())
        using (FileStream writeStream = new FileStream(@"C:\Program Files (x86)\xxxx\" + file, FileMode.Create))
        {
            int Length = 2048;
            Byte[] buffer = new Byte[Length];
            int bytesRead = responseStream.Read(buffer, 0, Length);
            int bytes = 0;
            while (bytesRead > 0)
            {
                writeStream.Write(buffer, 0, bytesRead);
                bytesRead = responseStream.Read(buffer, 0, Length);
                bytes += bytesRead;// don't forget to increment bytesRead !
                int iProgress = 0;
                int totalSize = (int)(fileSize) / 1000; // Kbytes
                if (totalSize > 0)
                {
                    iProgress = (bytes / 1000) * 100 / totalSize;
                }
                backgroundWorker1.ReportProgress(iProgress, totalSize);
            }
        }
        string zipFileExtension = Path.GetExtension(file);
        if (zipFileExtension == ".zip")
        {
            string zipToUnpack = @"C:\Program Files (x86)\xxxx\" + file;
            string unpackDirectory = @"C:\Program Files (x86)\xxxx\";
            using (ZipFile zip1 = ZipFile.Read(zipToUnpack))
            {
                foreach (ZipEntry ze in zip1)
                {
                    ze.Extract(unpackDirectory, ExtractExistingFileAction.OverwriteSilently);
                }
            }
        }
    }
}
public static class FTPSettings
{
    public static string IP { get; set; }
    public static string UserID { get; set; }
    public static string Password { get; set; }
}
public string[] ReadFileList()
{
    //Debugger.Break();
    string[] mydownloadFiles;
    StringBuilder myresult = new StringBuilder();
    //WebResponse myresponse = null;
    StreamReader myreader = null;
    FtpWebRequest myreqFTP = null;
    try
    {
        FTPSettings.IP = "xx.xx.xxx.xxx/TextureData";
        FTPSettings.UserID = "xxxx";
        FTPSettings.Password = "xxxx";
        myreqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://" + FTPSettings.IP + "/"));
        myreqFTP.Method = WebRequestMethods.Ftp.ListDirectory;
        myreqFTP.UseBinary = true;
        myreqFTP.Credentials = new NetworkCredential(FTPSettings.UserID, FTPSettings.Password);
        FtpWebResponse response = (FtpWebResponse)myreqFTP.GetResponse();
        myreader = new StreamReader(response.GetResponseStream());
        string myline = myreader.ReadLine();
        while (myline != null)
        {
            myresult.Append(myline);
            myresult.Append("\n");
            myline = myreader.ReadLine();
        }
        // to remove the trailing '\n'
        myresult.Remove(myresult.ToString().LastIndexOf('\n'), 1);
        return myresult.ToString().Split('\n');
    }
    catch (Exception ex)
    {
        if (myreader != null)
        {
            myreader.Close();
        }
        mydownloadFiles = null;
        return mydownloadFiles;
    }
}