From Release 9.0(1) onward, Cisco Unified Communications Manager (Unified CM) and IM and Presence Service software versions must match. For two software versions to match, they must have the same major and minor release number. Major and minor release numbers are defined as follows:
where 9 = major release number, x = minor release number and y = maintenance release number.
For example, IM and Presence Release 220.127.116.1100-4 is compatible with Unified CM Release 18.104.22.168000-2, but it is not compatible with Unified CM Release 22.214.171.12400-3. Similarly, Unified CM Release 126.96.36.19900-6 is not compatible with IM and Presence Release 188.8.131.5200-9.
You cannot upgrade IM and Presence to Release 9.0(1) unless Unified CM is running Release 9.0(1) on the active or inactive partition. You must upgrade Unified CM before you can upgrade IM and Presence to the matching version.
If you use Platform Administrative Web Services (PAWS) Management to upgrade IM and Presence, do not attempt to upgrade and reboot to IM and Presence Release 9.0(1) if the active partition on Unified CM is running an incompatible software version. If you do, the upgrade will fail, as expected, but the failure will not be reported until near the end of the upgrade process. You will also experience system downtime when the system reboots.
The delayed upgrade failure notification applies only to upgrades that are performed with PAWS Management. If you perform the upgrade through Cisco Unified IM and Presence Operating System Administration or through the CLI, the upgrade failure notification is displayed at the beginning of the upgrade.
The order in which you upgrade Unified CM and IM and Presence is very important.