Problem

B2Bi transfers to a Globalscape SFTP server fail in the middle of the transfers.

One version known to have this issue is SSH-2.0-7.7.1.0_openssh GlobalSCAPE but there could be others as well.

Message tracker shows error:

Interrupted: com.cyclonecommerce.tradingengine.transport.UnableToProduceException: SshException. Unexpected error. Attempted put path:

Log file shows:

2019-01-17 16:00:19,896 - ERROR [Worker4-42184] (SftpClient) - SSH exception during transfer [1]com.maverick.ssh.SshException: IO error received from remoteSocket closed [java.net.SocketException]

Resolution

This is caused by a bug in Globalscape SFTP server. It cannot handle the default maximum packet size of 32768 bytes which is the maximum value allowed according to RFC standard.

Until Globalscape resolves this issue, as a workaround open the partner delivery exchange point, go to the Advanced tab, and reduce the value for "Maximum block size per downloading packet" from default 32768 to something else. You have to try different values. One that worked when tested was 16000.