Omnissa Provisioning Fails with InsufficientHostMemoryCapacityFault

Products

• VMware vCenter Server

Issue/Introduction

During the provisioning or desktop recovery process in Omnissa, a machine fails to deploy.

• Omnissa Error: A provisioning error occurred for machine <MACHINE_NAME>

• vCenter vpxd.log Trace:

2026-03-13T12:05:15.270Z warning vpxd[06814] [Originator@6876 sub=vmmoVm opID=1d18####-01] VM <MACHINE_NAME> has no cached VMX config.
2026-03-13T12:05:15.308Z error vpxd[06814] [Originator@6876 sub=VmProv opID=1d18####-01] Get exception while executing action vpx.vmprov.InvokeCallbacks:
--> (vim.fault.InsufficientHostMemoryCapacityFault) {
-->    faultMessage = (vmodl.LocalizableMessage) [
-->       (vmodl.LocalizableMessage) {
-->          key = "com.vmware.drs.constraints.mem.InsufficientHostMemoryCapacityFault", 
-->          arg = (vmodl.KeyAnyValue) [
-->             (vmodl.KeyAnyValue) { key = "requested", value = 17179869184 }, 
-->             (vmodl.KeyAnyValue) { key = "unreserved", value = 157286400 }
-->          ]
-->       }
-->    ]
--> }

Environment

VMware vCenter 8.x

Cause

This error is a "Admission Control" rejection. It occurs when the vCenter Server determines that the target host or cluster cannot guarantee the physical memory resources required to safely power on a virtual machine.

Resolution

• Verify and reduce memory reservations on the virtual machine, parent template, or master image to release locked physical RAM.

• Check Resource Pool and Cluster Admission Control settings to ensure failover policies or fixed limits aren't blocking available capacity.

• Verify workload balance across the cluster and migrate VMs to hosts with higher unreserved capacity or add physical RAM to the hardware.

• Check the VM's configured memory size and overhead to ensure the request does not exceed the host's actual available physical resources.

• Verify memory distribution in vSphere Client by navigating to Hosts and Clusters > Select Host (or Cluster) > VMs tab (add the Memory Reservation column for visibility).

Additional Information

For reference see Omnissa KB:

VC_FAULT_FATAL - The host does not have sufficient memory resources to satisfy the reservation.