GWIA: Error Listen Port is already in use [856A]

  • 3243680
  • 11-Jul-2006
  • 06-Jun-2013


Novell NetWare 6.5
Novell GroupWise 7 Support Pack 1
Novell GroupWise 7 Internet Agent


Unable to connect to GWIA using POP3 client
Error loading GWIA:

Error: "Error Listen Port is already in use. [856A]"
Error: "Shutting down thread: GWPOP-Listener"

Below is a section of the GWIA log file (in Verbose mode) showing the errors

16:59:50 352 Starting GWPOP-Listener
16:59:50 344 Error Listen Port is already in use. [856A]
16:59:50 344 Shutting down thread: GWPOP-Listener
16:59:50 344 Shutting down thread: GWTCP-Dispatcher
16:59:51 34E Exiting GWTCP-Dispatcher
16:59:52 352 Exiting GWPOP-Listener


Even though the symptom was that POP3 users could not connect, the issue was caused by a conflict on the IMAP port 143 (the GroupWise POA also had IMAP enabled). Because GWIA detected that port 143 was already in use, it shut down both the POP and IMAP listener threads.

Since you cannot have two processes listening on the same port, either disable IMAP on the one of the Agents or change the port to a port not in use by another process. You can also set the IMAP port to "0" in ConsoleOne to disable IMAP on GWIA.