Virtual Machine Not Starting? Fixes for VirtualBox, VMware and Hyper-V
Read the exact error first, then work through the five usual causes: virtualization off in firmware, Hyper-V conflicts, low RAM, stuck saved states and boot order.
A virtual machine not starting usually comes down to one of five things: virtualization off in the firmware, Hyper-V holding the CPU, too little free RAM, a stuck saved state, or a boot setup that misses the ISO. The error message tells you which, so read it first.
Steps cover VirtualBox 7.2, VMware Workstation 26H1 and Hyper-V on Windows 10 and 11.
Virtual Machine Not Starting? Match the Exact Error First
Most cases of a virtual machine not starting leave a code or a sentence you can match:
| Error text or code | Seen in | Likely cause |
|---|---|---|
| VERR_VMX_MSR_ALL_VMX_DISABLED, VERR_SVM_DISABLED | VirtualBox | VT-x or AMD-V off in firmware |
| VERR_VMX_NO_VMX | VirtualBox | No VT-x visible: the CPU lacks it, Hyper-V hides it, or VirtualBox is itself inside a VM |
| VERR_VMX_IN_VMX_ROOT_MODE, VERR_SVM_IN_USE | VirtualBox | Another hypervisor holds the CPU (on Linux hosts, usually KVM) |
| VERR_NEM_NOT_AVAILABLE, VERR_NEM_VM_CREATE_FAILED | VirtualBox | Hyper-V mode failed: enable Windows Hypervisor Platform or turn Hyper-V off |
| supR3HardenedWinReSpawn, VERR_SUP_VP_* | VirtualBox | Hardening check failed: reinstall, check security software |
| “Device/Credential Guard are not compatible” or “does not meet minimum requirements” | VMware | Hyper-V on; Workstation, Windows or CPU too old |
| “The hypervisor is not running” or 0x80370102 | Hyper-V, WSL2 | Hypervisor or Virtual Machine Platform not loaded |
| VERR_VM_DRIVER_NOT_INSTALLED | VirtualBox | Driver missing: reinstall VirtualBox |
| Resume fails or hangs | All three | Saved state or snapshot |
| Powers on, nothing boots | All three | Boot order or ISO |
If the generic E_FAIL (0x80004005) is your only clue to a virtual machine not starting, read the log from the end up to the first error: Logs in the VM’s tools menu in VirtualBox Manager, or vmware.log beside the .vmx file.
VirtualBox 7.1 and later hide some settings in Basic mode, the default on new installs; switch to Expert under File > Preferences. Older guides’ Enable VT-x/AMD-V checkbox was dropped after 6.0.
VT-x or AMD-V Is Switched Off in the Firmware
VirtualBox has needed Intel VT-x or AMD-V since version 6.1 dropped its software-only mode, and Hyper-V needs it too, so the firmware is the first suspect for a virtual machine not starting on a PC that has never run one.
Run systeminfo in Command Prompt: every line under Hyper-V Requirements should read Yes. If it says a hypervisor has been detected, virtualization is on, and Hyper-V is the likelier reason for your virtual machine not starting: skip to the Hyper-V section.
If the firmware line reads No, turn on the setting (Intel Virtualization Technology, VT-x, AMD-V or SVM). Microsoft’s enable virtualization guide links to PC makers’ steps and warns that changing other firmware settings can lock you out of Windows.
Hyper-V or Memory Integrity Is Blocking VirtualBox and VMware
Only one program can use VT-x or AMD-V at a time. Microsoft says that while the Hyper-V hypervisor runs, VirtualBox and VMware may fail to start VMs or fall back to a slower mode. WSL2, Windows Sandbox, Credential Guard and Memory Integrity all use it, so it’s a likely cause of a virtual machine not starting after a Windows update.
If msinfo32 says “A hypervisor has been detected,” pick a way out:
Update VMware
Workstation 15.5.5 and later run on Hyper-V with Windows 10 build 19041.264 or newer, an Intel Sandy Bridge or AMD Bulldozer CPU or newer, and Windows Hypervisor Platform on.
Update VirtualBox
Version 6.0 and later run VMs through Hyper-V, often much slower, if Windows Hypervisor Platform is on. A green turtle in the VM window’s status bar marks this mode; a blue chip with a V means native VT-x/AMD-V.
Turn Hyper-V off
For full speed or nested VMs. VMware’s Hyper-V mode can’t offer Virtualize Intel VT-x/EPT or AMD-V/RVI (VM > Settings > Hardware > Processors).
Turning Hyper-V off
Per Microsoft’s Hyper-V compatibility article, open Control Panel > Programs and Features > Turn Windows features on or off, expand Hyper-V > Hyper-V Platform and clear Hyper-V Hypervisor. Oracle’s troubleshooting chapter adds Virtual Machine Platform and Windows Hypervisor Platform, which load the hypervisor even on Home; clear Windows Sandbox too. Restart and rerun msinfo32: if it still reports a hypervisor, Memory Integrity or Credential Guard is holding it.
Or stop the hypervisor loading at boot from an admin Command Prompt, then restart:bcdedit /set hypervisorlaunchtype off
Memory Integrity and Credential Guard can’t run meanwhile; undo it with bcdedit /set hypervisorlaunchtype auto when done. With the hypervisor fully off, WSL2 and Windows Sandbox stop until you reverse the change.
Turning Memory Integrity off may fix a virtual machine not starting, but it removes a guard that keeps malicious code out of the Windows kernel, so update your hypervisor first and ask IT on a work PC. The switch is under Windows Security > Device security > Core isolation details > Memory integrity; restart, and turn it back on the same way afterward.
Hyper-V Virtual Machine Not Starting: “The Hypervisor Is Not Running”
When Hyper-V says the hypervisor is not running, it wasn’t loaded at boot, often after a bcdedit change for another hypervisor, or with virtualization off in firmware. In an admin Command Prompt, run:bcdedit /enum | findstr -i hypervisorlaunchtype
If it shows Off, run bcdedit /set hypervisorlaunchtype auto and restart.
Still failing? Check that Hyper-V Hypervisor is ticked in Windows Features, the Hyper-V Virtual Machine Management service is running, and the PC has Windows 10 or 11 Pro, Enterprise or Education and a 64-bit CPU with SLAT.
Virtual Machine Platform won’t enable, or WSL2 shows 0x80370102
This WSL2 error (“a required feature is not installed”) means Virtual Machine Platform is off or the hypervisor isn’t running. In an admin Command Prompt, enable it, check firmware and bcdedit, then restart:dism.exe /online /enable-feature /featurename:VirtualMachinePlatform /all /norestart
If DISM fails, note its error code, install pending updates and retry. CPUs without SLAT can’t run WSL2.
Not Enough Free RAM on the Host
A VM’s memory must be free when it starts: VirtualBox requests the full Base Memory at power-on, and Hyper-V needs RAM for the host plus every running VM. If you find your virtual machine not starting only while heavy apps are open, this is the likely cause.
Close apps, or lower the allocation with the VM off, leaving the guest enough to boot: Settings > System > Motherboard in VirtualBox, VM > Settings > Hardware > Memory in VMware, Settings > Memory > Startup RAM in Hyper-V Manager.
Virtual Machine Not Starting From a Saved State or Snapshot
A virtual machine not starting after you saved or suspended it is probably tripping over that saved state. VMware documents one case: a VM suspended, or snapshotted while running, with Hyper-V off may not resume once Hyper-V, Memory Integrity or WSL2 is on.
Discarding a saved or suspended state is like pulling the guest’s power plug: unsaved work is lost and the guest disk may be left inconsistent, though the VM stays. Back up first: with VirtualBox or VMware closed, copy the whole VM folder plus any disks stored outside it; in Hyper-V Manager, use Action > Export.
Resume in the old mode
For the VMware case, turn Hyper-V off for now, resume, shut the guest down properly, then turn Hyper-V back on.
Discard the state
VirtualBox: Discard on the toolbar, or Machine > Discard Saved State. VMware: VM > Power > Power Off, then confirm. Hyper-V Manager: right-click the VM, Delete Saved State.
Fix snapshots in the app
Revert or delete snapshots only in VMware’s Snapshot Manager, VirtualBox’s Snapshots tool or Hyper-V’s Checkpoints pane, never by deleting .vmdk, .vdi or .avhdx files.
Won’t Boot From the ISO? Check Boot Order and Firmware
Sometimes what looks like a virtual machine not starting is one that powers on to a black screen or “No bootable medium found”: the guest finds nothing to boot.
- VirtualBox. Boot Device Order (Settings > System > Motherboard) applies only to BIOS VMs, where F12 at the splash screen also picks a device. Attach the ISO under Storage. Windows 11 needs EFI, TPM 2.0 and Secure Boot, all on the Motherboard tab, set before installing.
- VMware. Under VM > Settings > Hardware > CD/DVD, tick Connect at power on and point Use ISO image file at the ISO. VM > Power > Power On to Firmware lets you pick the boot device.
- Hyper-V. Generation 2 VMs boot ISOs only from a SCSI DVD drive, which New-VM doesn’t add; put it first under Settings > Firmware. For Linux, set the Secure Boot template under Settings > Security to Microsoft UEFI Certificate Authority.
On EFI VMs, Hyper-V Generation 2 included, a Windows ISO shows “Press any key to boot from CD or DVD” for only a few seconds. Miss it and the VM skips to network (PXE) boot, which looks like a virtual machine not starting from the ISO: restart, click into the VM and press a key.
Virtual machine not starting after a settings change or a move?
Switching the firmware type after install can stop VirtualBox and VMware guests booting, and Oracle warns against changing ACPI or I/O APIC after installing Windows: change them back. If you moved the VM, re-add it instead of hand-editing the .vbox or .vmx file: Machine > Open in VirtualBox 7.2 (Machine > Add in 7.1 and earlier), File > Open in VMware.
Frequently Asked Questions
Why is my virtual machine not starting after a Windows update?
Often the update, or a feature it turned on, started the Hyper-V hypervisor, so VirtualBox and VMware fail or slow down.
Why is my virtual machine not starting even though VT-x is enabled?
Another hypervisor is holding it, such as Hyper-V on Windows or KVM on Linux. Check msinfo32, then see the Hyper-V section.
What if the virtual machine got stuck while starting?
Give it a few minutes, since a slow first boot can look like a virtual machine not starting. Then force it off, losing unsaved guest work: Close > Power Off on its right-click menu in VirtualBox Manager, VM > Power > Power Off in VMware, Turn Off in Hyper-V Manager. If that hangs, end VirtualBoxVM.exe in Task Manager, or for Hyper-V the vmwp.exe whose user name is the VM’s ID.
Work Through It in This Order
Start with the exact error, then check firmware virtualization, Hyper-V conflicts, free RAM, saved states and boot order. Still stuck with a virtual machine not starting? Update your hypervisor and read the new log from the bottom up.
More fixes are in our software and apps guides. If the host misbehaves, see what to do when Windows won’t let you sign in. And test unknown downloads in a VM: on the host, some leave Chrome switching to Yahoo.
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