C# FTP ListDirectoryDetails Problem

I try to read file list from FTP from direcotry that contains over 1000 files.

I do it like this :

    public static FtpWebRequest GetRequest(string uri)
    {
        FtpWebRequest req = (FtpWebRequest)FtpWebRequest.Create(new Uri(uri));
        req.Credentials = new NetworkCredential("login", "password");
        req.KeepAlive = false;
        req.UseBinary = false;
        req.UsePassive = true;
        return req;
    }

    public static bool CheckConnection()
    {
        FtpWebResponse respSize = null;
        try
        {
            FtpWebRequest reqFTP = GetRequest(@"ftp://myftp.com");
            reqFTP.Method = WebRequestMethods.Ftp.ListDirectoryDetails;
            respSize = (FtpWebResponse)reqFTP开发者_Python百科.GetResponse();
            respSize.Close();
            respSize = null;
            reqFTP.GetResponse().Close();

            return true;
        }
        catch (Exception ex)
        {

        //...
        }
        finally
        {
            if (respSize != null)
                respSize.Close();
        }
        return false;
    }

I get an error:

The remote server returned an error:

(451) Local error in processing.

at System.Net.FtpWebRequest.SyncRequestCallback(Object obj)

at System.Net.FtpWebRequest.RequestCallback(Object obj)

at System.Net.CommandStream.Dispose(Boolean disposing)

at System.IO.Stream.Close()

at System.IO.Stream.Dispose()

at System.Net.ConnectionPool.Destroy(PooledStream pooledStream)

at System.Net.ConnectionPool.PutConnection(PooledStream pooledStream, Object owningObject, Int32 creationTimeout, Boolean canReuse)

at System.Net.FtpWebRequest.FinishRequestStage(RequestStage stage)

at System.Net.FtpWebRequest.SyncRequestCallback(Object obj)

at System.Net.FtpWebRequest.RequestCallback(Object obj)

at System.Net.CommandStream.Abort(Exception e)

at System.Net.CommandStream.CheckContinuePipeline()

at System.Net.FtpWebRequest.DataStreamClosed(CloseExState closeState)

at System.Net.FtpDataStream.System.Net.ICloseEx.CloseEx(CloseExState closeState)

at System.Net.FtpDataStream.Dispose(Boolean disposing)

at System.IO.Stream.Close()

at System.Net.FtpWebResponse.Close()

at CheckConnection()

does anyone knows what is going on ?

regards Marcin

From RhinoSoft (makers of the FTP software Serv-U):

"A 451 reply code may be sent in response to any command initiating a file transfer. It is a transient negative response, which means the error condition is a temporary one. It is usually sent in response to the server encountering an unexpected local error when processing data it is transferring or receiving. In this case, the client is encouraged to restart the FTP transaction and try again." [1]

So, it may be an issue with communication between your software and the FTP server, not necessarily an issue with your software itself.

It can't hurt to increase the length of the Timeout property of FtpWebRequest, but that's not likely to be the cause based on my research.