If you run the Set CPU Count or Set Memory actions with an unsupported value on a virtual machine, the virtual machine might be left in an unusable state. That outcome requires you to resolve the problem in vCenter Server.


You cannot power on a virtual machine after you successfully run the Set CPU Count or Set Memory actions. When you review the messages in Recent Tasks for the failed Power On VM action, you see messages stating that the host does not support the new CPU count or new memory value.


Because of the way that vCenter Server validates changes in the CPU and memory values, you can use the VMware Aria Operations actions to change the value to an unsupported amount. This change can happen when you run the action when the virtual machine is powered off.

If the object was powered on, the task fails, but rolls back any value changes and powers the machine back on. If the object was powered off, the task succeeds and the value is changed in vCenter Server. However, the target object is left in a state where you cannot power it on using either actions or the vCenter Server without manually changing the CPU or memory to a supported value.


  1. From the left menu, click Administration, then select Recent Tasks from the left pane.
  2. In the task list, locate your failed Power On VM action, and review the messages associated with the task.
  3. Look for a message that indicates why the task failed.
    For example, if you ran a Set CPU Count action on a powered off virtual machine to increase the CPU count from 2 to 4, but the host does not support 4 CPUs. The Set CPU tasks reported that it completed successfully in recent tasks. However, when you attempt to power on the virtual machine, the tasks fails. In this example, the message is Virtual machine requires 4 CPUs to operate, but the host hardware only provides 2.
  4. Click the object name in the Recent Task list.
    The main pane updates to display the object details for the selected object.
  5. Click the Actions menu on the toolbar and click Open Virtual Machine in vSphere Client.
    The vSphere Web Client opens with the virtual machine as the current object.
  6. In the vSphere Web Client, click the Manage tab and click VM Hardware.
  7. Click Edit.
  8. In the Edit Settings dialog box, change the CPU count or memory to a supported value and click OK.
    You can now power on the virtual machine from the Web client or from VMware Aria Operations.