Eu procurei e encontrei outras perguntas sobre isso, mas nenhuma resolveu meus problemas. Estou tentando fazer upload de um arquivo via FTP usando um código de amostra do MSDN. Recebo o erro O servidor remoto retornou um erro: (550) Arquivo indisponível (por exemplo, arquivo não encontrado, sem acesso) nesta linha: ftpstream.Close ();

    string inputfilepath = @"C:\DWF\test.txt";
    string ftpfilepath = "/abc/def/hij/klm/nop/test.txt";
    string ftphost = "my-ser-ver1:2121";
    //here correct hostname or IP of the ftp server to be given  

    string ftpfullpath = "ftp://" + ftphost + ftpfilepath;
    FtpWebRequest ftp = (FtpWebRequest)FtpWebRequest.Create(ftpfullpath);
    ftp.Credentials = new NetworkCredential("user", "pass");
    //userid and password for the ftp server to given  

    ftp.KeepAlive = true;
    ftp.UseBinary = true;

    ftp.Method = WebRequestMethods.Ftp.UploadFile;
    FileStream fs = File.OpenRead(inputfilepath);
    byte[] buffer = new byte[fs.Length];
    fs.Read(buffer, 0, buffer.Length);
    fs.Close();
    Stream ftpstream = ftp.GetRequestStream();
    ftpstream.Write(buffer, 0, buffer.Length);
    ftpstream.Close(); 

Verifiquei duas vezes o URI quanto a espaços em branco e não há nenhum. Consigo concluir esta tarefa usando o filezilla com o mesmo login de usuário. Não existe um diretório padrão do oddball que já faça parte do meu URI. Uma coisa é certa: estou me conectando a um servidor unix; talvez exista uma configuração que esteja faltando?

Edit # 1 (log de erro adicionado do System.Net)

System.Net Information: 0 : [7584] FtpControlStream#62182359 - Received response [220 Oracle Content Services FTP Server ready.]

System.Net Information: 0 : [7584] FtpControlStream#62182359 - Sending command [USER myuser]

System.Net Information: 0 : [7584] FtpControlStream#62182359 - Received response [331 Password required for myuser.]

System.Net Information: 0 : [7584] FtpControlStream#62182359 - Sending command [PASS ********]

System.Net Information: 0 : [7584] FtpControlStream#62182359 - Received response [230 Login successful.]

System.Net Information: 0 : [7584] FtpControlStream#62182359 - Sending command [OPTS utf8 on]

System.Net Information: 0 : [7584] FtpControlStream#62182359 - Received response [500 Command not supported: OPTS]

System.Net Information: 0 : [7584] FtpControlStream#62182359 - Sending command [PWD]

System.Net Information: 0 : [7584] FtpControlStream#62182359 - Received response [257 "/"]

System.Net Information: 0 : [7584] FtpControlStream#62182359 - Sending command [TYPE I]

System.Net Information: 0 : [7584] FtpControlStream#62182359 - Received response [200 TYPE set to I.]

System.Net Information: 0 : [7584] FtpControlStream#62182359 - Sending command [PASV]

System.Net Information: 0 : [7584] FtpControlStream#62182359 - Received response [227 Entering Passive Mode (10,8,9,50,77,53)]

System.Net Information: 0 : [7584] FtpControlStream#62182359 - Sending command [STOR abc/def/hij/klm/nop/test.txt]

System.Net Information: 0 : [7584] FtpControlStream#62182359 - Received response [150 Ok to send data.]

System.Net Verbose: 0 : [7584] Exiting FtpWebRequest#10964107::GetRequestStream() 

System.Net Information: 0 : [7584] FtpControlStream#62182359 - Received response [550 Access denied.]

System.Net Information: 0 : [7584] FtpWebRequest#10964107::(Releasing FTP connection#62182359.)