You must uninstall Update Rollup 1 prior to installing Update Rollup 2.
If you install Update Rollup 2 from Microsoft Update Catalog without uninstalling Update Rollup 1, you should uninstall both 2 and 1 before installing 2 again.
Also note that Update Rollup 2 won’t be available through WSUS if Update Rollup 1 is installed.
More information about this can be found here: http://blogs.technet.com/b/scvmm/archive/2013/04/23/update-on-system-center-2012-sp1-update-rollup-2-ur2-for-virtual-machine-manager.aspx
After you have installed Update Rollup 2, you must update the VMM agents on your servers in Fabric. The servers will have a warning that requires your attention, and you can simply right click on the servers and proceed to update the agent. This won’t require any reboots.
A lot has been fixed related to networking, virtual network adapters, logical switches, uplink port profiles, extensions, classification and so on. I have encountered many of these bugs in the field myself and it’s great to have them solved.
Virtual Machine Manager Server (KB2826405) and Administration Console (KB2826392)
The SUSE Linux Enterprise Server 11 operating system is missing from the Linux OS list.
A virtual machine cannot start after migration from Windows 7 to Windows 8 when the DiscardSavedState method is used.
A connection to the VMware virtual machine remote console session cannot be established.
Externally published VMNDs are filtered incorrectly.
When you remove a virtual switch extension property or edit a virtual switch extension manager connection string, a user-interface generated script also removes the HostGroups that are associated with VSEM.
UPPSet is not set on a physical network adapter when you add the network adapter to a team and when the network adapter is the first in the list of network adapters.
The default gateway is missing on a host virtual network adapter after you add a second physical network adapter to the logical switch.
Static IP pool that has the first address in a subnet fails for external network type.
VMM crashes during host refresher when VMM is unable to create a CimSession with the remote host.
Standard (legacy) virtual switch creation on Windows 8 hosts with management virtual network adapter does not preserve the IP properties of the physical network adapter.
The administration user interface crashes with a NullReferenceException error when you click Remediate on a host instead of a virtual network adapter.
The Virtual Machine Manager user interface displays a network adapter in a "Not Connected" state.
The Virtual Machine Manager stops responding with high CPU usage for five to ten minutes when you configure a VMND that has 2,000 network segments.
The host virtual network adapter property for a management adapter does not show port classification.
Live Migration fails at 26 percent when the network adapter is attached to an isolated virtual machine network.
The Virtual Machine Manager Service crashes when a virtual machine that does not have a port profile is migrated to a cluster by using a logical switch that has a default port profile set.
Running Dynamic Optimizer on a cluster with incompatible host CPUs causes a Virtual Machine Manager Service crash.
The Host refresher crashes for any host that has the RemoteFX role enabled.
The minimum memory for dynamic memory greater than 32GB is a security risk.
The status of the network adapter is displayed as Not Connected in Virtual Machine Manager.