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Question:

Random SFTP upload failures: Recieved data for nonexistent channel 0

May 20 '15 at 07:41

I'm developing a file upload application for my company and have repeatedly and randomly encountered this issue. I know the bulk of the code works, as the majority (~85%) of the time the upload completes without any issue. However, certain batches will fail repeatedly, posting the following error message:

(The file paths are valid, I redacted some info from them)

UploadFile:
    DllDate: Jan 21 2015
    ChilkatVersion: 9.5.0.47
    UnlockPrefix: xxxxxxxx
    Username: xxxxxxx
    Architecture: Little Endian; 64-bit
    Language: Windows Java
    VerboseLogging: 0
    SshVersion: SSH-2.0-Connect:Enterprise_UNIX_2.4.04 Build 00
    SftpVersion: 3
    handle: 00000000
    fromPath: \..COLL_700578_898577_DSK95_20150514_20150515_20150515012317.zip
    uploadFile:
      socketOptions:
        SO_SNDBUF: 8192
        SO_RCVBUF: 8192
        TCP_NODELAY: 1
      --socketOptions
      handle: 00000000
      fromLocalPath: \..COLL_700578_898577_DSK95_20150514_20150515_20150515012317.zip
      localFileSize2: 221344467
      writeDataSource:
        smallWindowSizeUpload:
          getWriteStatusReplies:
            Received EOF
            Failed to read SFTP packet.
            Failed to read packet (write status response) in SFTP file upload
            numStatusMessagesRequired: 56091
            numStatusMessagesReceived: 56090
          --getWriteStatusReplies
          Failed to get write status replies (2)
          getWriteStatusReplies:
            readChannelData_2:
              genRead_1:
                Received CHANNEL REQUEST message
                requestType: exit-status
                wantReply: 0
                exitStatusCode: 255
                Sent SSH Channel CLOSE
              --genRead_1
            --readChannelData_2
            Received Close
            Failed to read SFTP packet.
            Failed to read packet (write status response) in SFTP file upload
            numStatusMessagesRequired: 56091
            numStatusMessagesReceived: 56090
          --getWriteStatusReplies
          Failed to get write status replies (2)
          getWriteStatusReplies:
            readChannelData_2:
              genRead_1:
                Received DISCONNECT message
                DisconnectReason: Received data for nonexistent channel 0.
              --genRead_1
            --readChannelData_2
            Received SSH disconnect.
            disconnectCode: 2
            disconnectReason: Received data for nonexistent channel 0.
            Failed to read SFTP packet.
            Failed to read packet (write status response) in SFTP file upload
            numStatusMessagesRequired: 56091
            numStatusMessagesReceived: 56090
          --getWriteStatusReplies
          Failed to get write status replies (2)
          No channel for writing.
          ------------------------------------------------
          totalNumBytesSent: 120369152
          totalTimeSendingMs: 19766
          totalTimeReadingMs: 14049
        --smallWindowSizeUpload
      --writeDataSource
      uploadFileSuccess: 0
    --uploadFile
    Failed.
  --UploadFile
--ChilkatLog

I've been unable to pinpoint any single common element between the failed batches, they cover a variety of sizes and content. The failure is always the same though: a single missing packet after data received for a nonexistent channel. Occasionally, reattempting the upload will work, but that success is a rarity.

Has anyone encountered this issue before or know how to solve it?

---

Answer

Try the latest Chilkat version 9.5.0.49 (http://www.chilkatsoft.com/java.asp). If you still see the problem, then let me know if you can provide a test account on that particular server and we can continue with this issue offline (support@chilkatsoft.com). I haven't had any other similar problem reports..