This topic covers some common issues you may encounter when using Hyper-V. For more in-depth troubleshooting information based on Hyper-V events, see the Hyper-V troubleshooting content in the Windows Server 2008 Technical Library (
What problem are you having?
I installed the Hyper-V role and can create or import a virtual machine, but I can’t start the virtual machine.
Cause: The hypervisor is not running. The following error appears in the System event log: “The virtual machine could not be started because the hypervisor is not running.”
Solution: The physical computer must meet specific hardware requirements to run the hypervisor. For more information, see Hyper-V Installation Prerequisites. If the computer does not meet the requirements, you will not be able to use that computer to run virtual machines. If the computer meets the requirements and the hypervisor is not running, you might need to enable the settings for hardware-assisted virtualization and hardware-enforced Data Execution Prevention (DEP) in the BIOS. If you modify these settings, you must turn off the power to the computer and then turn it back on. Restarting the computer does not apply the changes to the settings.
Cause: The virtual disk that serves as the system disk is attached to a SCSI controller.
Solution: Attach the system disk to an IDE controller. For instructions, see Configure Disks and Storage.
Cause: The virtual machine is configured to use a physical CD or DVD as the installation media, and the physical drive is in use.
Solution: A physical CD or DVD drive can be accessed by only one virtual machine at a time. Disconnect the CD or DVD from the other virtual machine and try again.
I cannot perform a network-based installation of a guest operating system.
Cause: The virtual machine is using a network adapter instead of a legacy network adapter, or the legacy network adapter is not connected to an appropriate external network.
Solution: Ensure that the virtual machine is configured with a legacy network adapter that is connected to an external network which offers installation services. For instructions about configuring network adapters, see Configure Networking.
A virtual machine pauses automatically.
Cause: A virtual machine will be paused automatically when the volume on which snapshots or virtual hard disks are stored runs out of available storage. The state of the virtual machine will be listed as “paused-critical” in Hyper-V Manager.
Solution: Create additional space on the drive by using Hyper-V Manager to apply or delete the snapshots individually. Or, to delete all of the snapshots, export the virtual machine without exporting the virtual machine data and then import the virtual machine.
When I try to create or start a virtual machine, I receive error messages about a “user-mapped section open”, “the specified network resource or device is no longer available”, or the “I/O operation aborted because of either a thread exit or an application request”.
Cause: This can be caused by antivirus software running in the management operating system when the real-time scanning component is configured to monitor the Hyper-V virtual machine files.
Solution: Exclude the virtual machine files from real-time scanning. For information about the specific files, see article 961804 in the Microsoft Knowledge Base (
Virtual machines have disappeared from the Hyper-V Manager console.
Cause: This can be caused by antivirus software running in the management operating system when the real-time scanning component is configured to monitor the Hyper-V virtual machine files.
Solution: Exclude the virtual machine files from real-time scanning. For information about the specific files, see article 961804 in the Microsoft Knowledge Base (
When I use Virtual Machine Connection, the mouse pointer appears as a dot or the mouse pointer is stuck in the virtual machine window.
Cause: Integration services are not installed in the guest operating system.
Solution: If the guest operating system is supported, integrations services are available for that operating system. Install the integration services to improve mouse integration. For instructions, see Install a Guest Operating System. If the guest operating system is not supported, you can use a key combination to move the mouse out of the virtual machine window. The default key combination is CTRL+ALT+LEFT ARROW.
When I try to control a virtual machine, I cannot use the mouse. I am using Remote Desktop Connection to connect to a server running Hyper-V.
Cause: When you use Hyper-V Manager to connect to a virtual machine, Virtual Machine Connection provides the connection to the virtual machine. However, use of Virtual Machine Connection within a Remote Desktop Connection session is not supported until integration services are installed. As a result, lack of mouse functionality is expected behavior.
Solution: Avoid using Virtual Machine Connection within a Remote Desktop Connection session until integration services are installed. There are several ways you can accomplish this:
- Install integration services. For instructions, see Install a Guest Operating System.
- Establish a Remote Desktop session directly to the virtual machine.
- Log on to the console of the server running Hyper-V and then use Virtual Machine Connection to connect to the virtual machine.
- On a supported client computer, install the Hyper-V management tools to install Virtual Machine Connection on the computer and establish a Virtual Machine Connection session to the virtual machine. For more information, see the Windows Server 2008 Technical Library (
https://go.microsoft.com/fwlink/?LinkId=143558 ).
When I open Device Manager in the guest operating system, some devices are listed as unknown devices.
Cause: Device Manager does not recognize devices that are optimized for use in virtual machines and run using Hyper-V until integration services are installed. The unknown devices that are identified in Device Manager differ depending on the guest operating system and may include: VMBus, Microsoft VMBus HID Miniport, Microsoft VMBus Network Adapter, and storvsc miniport.
 | Note |
Some optimized devices are not available for certain guest operating systems. When a device is not supported on a guest operating system, the device will not work. You cannot install the device driver manually to try to make the device work. For a list of the devices that are available on each supported guest operating system, see |
Solution: If the guest operating system is supported, integration services are available for that operating system. After you install the integration services, Device Manager will recognize the devices that are available for that guest operating system. For instructions, see Install a Guest Operating System.
I want to monitor the performance of a virtual machine, but the processor information displayed in Task Manager does not show the processor resources being used by the virtual machine.
Cause: Task Manager does not display CPU information for virtual machines.
Solution: To view CPU usage information for virtual machines running on a server running Hyper-V, use Performance and Reliability Monitor to view the data from Hyper-V performance counters. To open Performance and Reliability Monitor, click Start, click Run, and then type perfmon.
The following performance counters provide information when viewed on the management operating system (the operating system that runs the Hyper-V role):
- Hyper-V Hypervisor Logical Processor % Guest Run time: Identifies how much of the physical processor is being used to run the virtual machines. This counter does not identify the individual virtual machines or the amount consumed by each virtual machine.
- Hyper-V Hypervisor Virtual Processor %Guest Run time: Identifies how much of the virtual processor is being consumed by a virtual machine.
| Note |
There is no direct mapping of virtual processor consumption to logical processor consumption because the virtual processors can be scheduled on any of the logical processors. |