Problem
When you try to connect a new VM to a logical switch you get a lot of strange error messages related to missing ports or no available switch. The errors seem random.
Analysis
If you check the logical switch properties of an affected host, you will notice that the uplink profile is missing:
If you look at the network adapter properties of an affected VM, you will notice that the Logical Switch field is blank:
This is connected to a WMI problem. Some Windows updates uninstall the VMM WMI MOFs required for the VMM agent to manage the logical switch on the host. See details at MS Tech.
Solution
MOFCOMP to the rescue. Run the following commands in an administrative Powershell prompt. To update VMM you have to refresh the cluster/node. Note: Some versions use a different path to the MOF-files, so verify this if the command fails.
Mofcomp “%systemdrive%\Program Files\Microsoft System Center\Virtual Machine Manager\setup\scvmmswitchportsettings.mof” Mofcomp “%systemdrive%\Program Files\Microsoft System Center\Virtual Machine Manager\DHCPServerExtension\VMMDHCPSvr.mof” Get-CimClass -Namespace root/virtualization/v2 -classname *vmm*