In a Citrix Presentation Server farm, following Event Log messages are written by XTE service to Application Event log of farm member servers:
Event ID 110 "A CGP client attempted to reconnect to a CGP session that no longer exists"

Th​e following error messages may also be seen:
Event ID 112 "An error occurred when processing outgoing CGP downstream data"
- And -
Event ID 103 "An error occurred when processing incoming CGP downstream data"

Ensure all sessions are disconnected or logged off before placing the client into Standby or Hibernation mode.

Status

These Event Log error messages are by design.

Problem Cause

Under certain circumstances, these event messages can be written by XTE service to Application Event log of farm member servers, when a client attempts to reconnect to a session on a Citrix Presentation Server using Session Reliability and session no longer exists on farm member server.
This condition can occur, when the client device with active sessions has been placed in Standby or Hibernation mode and the Citrix Presentation Server hosting sessions was restarted before the client was restored to Normal mode.
In this scenario, the client restored to normal mode attempts to reconnect to sessions, considering that they are still available on Citrix Presentation Server. Since the server was restarted, these sessions no longer exist on the server and XTE service ends up writing above listed event log messages to Application Event log.