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A Hyper-V hypervisor is the core virtualization layer that allows multiple virtual machines to share the same physical hardware. It sits between the operating system, and the hardware, abstracting CPU, memory, storage, and networking resources so virtual machines can run independently.
However, when you try to boot VMs as usual, you may get the error prompt:
“An error occurred while attempting to start the selected virtual machine(s).”
“xxx failed to start”.
“Virtual machine could not be started because the hypervisor is not running”.
When you see the error, it means this virtualization layer failed to start or wasn’t loaded. As a result, no virtual machines can run, regardless of their individual configuration.
Don’t worry! In this article, we will explain why this error happen and help you out of the issue step by step.
Why hypervisor not running?
In practice, “hypervisor is not running” does not mean the VM itself is broken. Instead, it points to a host-level issue, where the underlying virtualization platform is unavailable. Below are the most common causes:
- BIOS / UEFI settings not properly configured: For example, DEP is perquisite for Hyper-V. If it is disabled, the hypervisor may fail. In addition, CPU virtualization extensions are disabled in BIOS/UEFI can also cause the problem.
- Hypervisor Launch Type Disabled in Boot Configuration: Windows controls this behavior through the Boot Configuration Data (BCD). If the hypervisor launch type is set to off, Windows will skip loading the hypervisor during startup, and the hypervisor will not be running.
- Conflicting virtualization Hypervisors: Most systems can only run one hypervisor at a time with full hardware access. When multiple virtualization platforms compete for the same CPU virtualization extensions, conflicts occur.
- Windows Updates or configuration changes: Windows updates occasionally introduce changes that affect virtualization. After such updates, systems that previously worked may suddenly fail to load the hypervisor.
- Corrupted System Files or Drivers: Hypervisor depends on low-level system components, including kernel modules, hardware Abstraction Layer, CPU, and chipset drivers. If these files become corrupted or inconsistent, the hypervisor may fail to initialize correctly
All the above causes prevent the hypervisor from being loaded before VMs even attempt to start.
How to Diagnose the Issue (Pre-Fix Checklist)
Before applying any fixes, let’s diagnose the actual cause.
Step 1. Check Virtualization Support
The first step is to confirm that the system meets all Hyper-V requirements at the hardware and OS level.
1. click Start, type “cmd“, right-click the “Command Prompt” result, and select “Run as administrator“.
2. Run the following command:
systeminfo
Scroll to the Hyper-V Requirements section and verify:
- VM Monitor Mode Extensions: Yes
- Virtualization Enabled in Firmware: Yes
- Second Level Address Translation (SLA): Yes
- Data Execution Prevention Available: Yes
If any of these items show “No”, Windows will not load the hypervisor, and virtual machines will fail to start. And it is caused by unsupported hardware or disabled firmware features.
Step 2. Check DEP & Virtualization in BIOS / UEFI
1. Reboot the system and press repeatly BIOS/UEFI key to enter BIOS/UEFI setup. The BIOS/UEFI key depends on the computer/server. If you don’t know, you can try F11, F12, F10, Delete.
2. Confirm the following options are enabled:
Intel VT-x / Intel VT-d or AMD-V
Data Execution Prevention (DEP), sometimes labeled as:
- Execute Disable Bit
- NX
- No Execute Memory Protection
If virtualization or DEP is disabled at this level, Hyper-V will not initialize—regardless of Windows configuration.
Step 3. Review Event Viewer Logs
When Hyper-V fails to start, Windows records detailed diagnostics in Event Viewer. These logs explain why the hypervisor failed to initialize.
1. Open Event Viewer
2. Navigate to “Windows Logs” > “System”.
3. Look for errors related to: Hyper-V, Hypervisor launch failures, Virtualization services.
Common indicators include:
- Event ID 3112, which typically means Windows attempted to start the hypervisor but it did not load successfully
- Messages indicating virtualization is unavailable or blocked
Event logs help distinguish between:
- Hardware or firmware limitations
- Boot configuration issues
- System-level conflicts or failures
Step 4. Verify Hyper-V Services & Boot Configuration
Hyper-V relies on both boot-time configuration and runtime services to function correctly. Make sure the hypervisor is allowed to load during system startup and required management services are available once Windows is running
You can check:
1. Ensure Hyper-V-related servers are: Present, running, Set to Automatic startup.
2. Important services include: Hyper-V virtual machine management, Hyper-V Host Compute Service
3. Confirm that the hypervisor is enabled in the Windows boot configuration.
How Fix Hyper-V Hypervisor is not running in Windows
Once the root cause has been identified, you can apply the appropriate fix. In most cases, the issue can be resolved without reinstalling the operating system by correcting configuration or system-level settings.
The solutions below are ordered from most common to less frequent, and can be applied step by step.
Solution 1. Enable Virtualization & DEP in BIOS
If hardware virtualization or DEP is disabled in BIOS/UEFI, the hypervisor cannot load during system startup.
Step 1. Reboot the system and press BIOS key repeatly when you see the first screen to enter BIOS / UEFI setup. If you don’t know the BIOS key, you can try F11, F12, F10, Delete.
Step 2. Locate CPU or Advanced settings
Step 3. Enable the following options:
- Intel VT-x / Intel VT-d or AMD-V
- Data Execution Prevention (DEP)
Step 4. Save changes and reboot the system.
Tip: On some systems, DEP may be labeled as Execute Disable Bit, NX, or No Execute Memory Protection.
After rebooting, Windows should be able to initialize the hypervisor normally.
Solution 2. Set Hypervisor Launch Type to Auto
Even when Hyper-V is installed, Windows may be configured not to load the hypervisor at boot.
To reenable it:
Step 1. Open Command Prompt as administrator
Step 2. Run the following command:
bcdedit /set hypervisorlaunchtype auto
Step 3. Restart Windows
This solution is especially effective if the error appeared after:
- Disabling Hyper-V temporarily
- Installing or removing other virtualization software
- Performing system recovery or boot repairs
Once the hypervisor is set to launch automatically, Hyper-V will load during startup, and virtual machines should start normally.
Solution 3. Roll Back Recent Windows Updates
In some cases, a recent Windows update may introduce changes that affect virtualization. Just roll back the recent Windows update to fix this problem.
To roll back a Windows update.
Step 1. Click the Start button > “Settings” > “Update & Security”.
Step 2. View installed update history. And identify updates that stalled before the issue occurred.
Step 3. Choose “Uninstall updates” and select the update to remove.
Solution 4. Update BIOS/UEFI and System Drivers
Outdated firmware or drivers can prevent proper hypervisor initialization. You can update the system BIOS/UEFI from the hardware manufacturer.
Make sure the Chipset drivers, CPU-related drivers, and firmware management utilities are the latest. These updates often improve virtualization stability and compatibility with newer Windows versions.
Solution 5. Check for Software Conflicts
Conflicts with other virtualization platforms can block Hyper-V from accessing hardware virtualization features. And Hyper-V VM will failed to start you will get the ” hypervisor is not running” error.
You can disable VMware Workstation, VirtualBox, or Legacy Docker configurations temporarily and disable security or sandboxing software that uses virtualization
After removing conflicts, reboot the system to ensure hardware virtualization resources are released.
Solution 6. Repair Windows System Files
If system files required by the hypervisor are corrupted, Hyper-V may fail to start consistently. Try the steps below to repair system integrity.
Step 1. Run Command Prompt as Administrator
Step 2. Run the following commands one by one:
sfc /scannow
dism /online /cleanup-image /restorehealth
These tools scan and repair corrupted system files, including components involved in hypervisor initialization.
When to Consider Reinstallation or Support
In most cases, the “hypervisor is not running” error can be resolved by correcting BIOS settings, boot configuration, or system services. However, there are situations where standard troubleshooting steps are no longer effective.
At this stage, it is important to evaluate whether deeper system repair or external support is the most efficient option.
1. Repeated Failures After All Fixes Are Applied
If you have tried all solutions above, the error continues to appear after every reboot, this often indicates deep system-level inconsistencies that are difficult to correct manually.
2. Persistent Errors in Event Viewer
Event Viewer provides valuable insight into system health. If logs continue to show:
- Repeated hypervisor initialization failures
- Kernel or virtualization-related errors during every startup
- Errors that persist even after configuration changes
This suggests underlying issues that go beyond simple misconfiguration, such as damaged core components or unstable firmware interactions.
3. Operating System Integrity Is Compromised
In some environments, system instability may be caused by:
- Failed or interrupted Windows update
- Disk errors or file system corruption
- Long-term driver inconsistencies
When multiple system components are affected, attempting to repair individual settings may introduce further instability. In these cases, a clean operating system reinstallation can be the fastest and most reliable way to restore virtualization functionality.
Regular Backup Hyper-V to Protect VMs
Virtual machines are highly dependent on host stability. When the hypervisor fails, VMs can become inaccessible instantly, even if their data is intact.
It is recommended to create a backup schedule for your VMs. So your VMs can be restored even if the Hyper-V host fails, and the downtime is minimized in the event of encountering a problem.
To address these challenges, Info2Soft i2Backup provides enterprise-grade backup and recovery for Hyper-V environments.
With i2Backup, organizations can:
- Perform agentless Hyper-V backups with minimal performance impact
- Ensure consistent protection for running virtual machines
- Recover VMs quickly after hypervisor failures or system rebuilds
- Centralize backup management for complex virtual environments
By combining proactive system maintenance with a reliable Hyper-V backup solution, organizations can reduce risk and ensure that virtualization issues—such as a hypervisor failing to start—do not lead to data loss or extended downtime.
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Conclusion
The “hypervisor is not running” error is typically caused by system-level configuration issues rather than problems with individual virtual machines. In most cases, the root cause can be traced back to disabled virtualization settings, incorrect boot configuration, software conflicts, or system integrity problems.
By taking approaches: verifying hardware and BIOS settings, reviewing boot configuration and services, analyzing event logs, and applying targeted fixes, administrators can resolve the issue efficiently.
Just as importantly, even a short hypervisor outage can make all VMs inaccessible. Create a reliable and regular Hyper-V backup strategy with i2Backup for your VMs.
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