1. First, if you are going from 8.X or lower TO 9.X, you need to install the following file from Cisco: 'ciscocm.cer_refresh_upgrade_v1.1.cop.sgn'. Do the install from the CER OS Administration page.
2. After this COP file is installed successfully, then you can do the upgrade to 9.X with this file: 'UCSInstall_CER_188.8.131.5200-1.sgn.iso' Again, on the CER OS Administration page.
NOTE** The file named 'Bootable_UCSInstall_CER_184.108.40.20600-1.sgn' is NOT the upgrade file. This file is for new installs only.
Once you do these two steps, you should be up to the 9.X version without issue. Keep in mind, it does take time to do this upgrade. When the server reboots going into the upgrade, expect it to take time.
Some screenshots of what I saw:
During the reboot, this is what I saw on the VMWare Console access below.
In the Console access below, you can see that once the upgrade was done, CLI shows the new version number (below).
Once you get the upgrade completed, make sure you change the version of CUCM you are connecting to on the CER Admin Utility page.
how long it took to upgrade cisco cer 8.6 to 9.0 per server?
Not sure I recall exactly. Sorry, that was a few months back.Delete