Error Message :
While performing a Zero Downtime Upgrade (ZDU) the point where the Agent is reconnecting will occasionally cause Java based agents (i.e. SAP, SQL, etc.) to crash.
The following error message is displayed and trace files are thrown.
U02003012 An unknown message from partner '##SYSTEMNAME##CPNUMBER' could not be processed
Shortly after the Agent crashes with the error messages described under "Error Message".
This occurs on SAP and other Java based Agents (SQL, RA,...) occasionally, it does not always occur.
The error was found with Agents in Version 12.0, but it is possible that older agents will also show this behavior