This article states why the Post Install Object Comparison job may fail with a "UNABLE TO ESTABLISH XMANAGER CONNECTION" error when installing a new release of CA DB2 tools for z/OS.
What can cause message UNABLE TO ESTABLISH XMANAGER CONNECTION when executing Post Install tasks for the CA Database Management Solutions for DB2 for z/OS?
z/OS 1.11 and above.
The previous release XMANAGER task was running when the install was being done caused the problem. The release associated with the XMANAGER task must match the release of the products being installed or accessed. A new XMANAGER task must be started under the current maintenance release being installed to resolve this problem.