Fixed: The CPU Has Been Disabled By the Guest Operating System

While running a virtual machine (VM), you may encounter an error message that the CPU has been disabled by the guest operating system. Power off or reset the virtual machine. After this error occurs, it can cause the VM to not function properly, which can affect personal or business operations. In this article, you will be provided with the cause of one of the problems and a solution.

Common Causes of the Error

Several factors can cause the CPU Disabled error, and the following are some common reasons.

1. Unsupported or Mismatched CPU features

Specific CPU features are required in some operating systems, notably macOS and some Linux distributions, which typically require SSE4.1, AVX, or VT-x. If the virtualized environment does not provide these required features, the guest operating system may disable the CPU.

2. Kernel Panic in the Guest OS

A kernel crash occurs when the guest operating system encounters a severe error that cannot be recovered from, which also typically causes the system to shut down or disable the CPU.

3. Incorrect Virtual Machine Configuration

In a virtual machine, an incorrect configuration (assigned CPU cores, hardware acceleration, or compatibility mode) can also cause the CPU disabled.

4. Corrupt or Incompatible Guest Operating System Installation

A corrupt or improperly installed operating system may prevent booting and thus disable the CPU.

How to Fix the CPU Has Been Disabled by the Guest Operating System

You can follow these steps to fix the error:

Step 1. Enable Virtualization in BIOS/UEFI

Ensure that virtualization is enabled for your system:

• For Intel CPUs: Enable Intel VT-x.
• For AMD CPUs: Enable AMD-V.

Restart the system and press F2, F10, F12, or Del, and enable virtualization under CPU Settings.

Step 2. Modify Virtual Machine CPU Settings

Increase Virtual CPUs: Some versions of the guest operating system require more than one virtual CPU. Increase the number of virtual processors assigned in the virtual machine settings.

Disable Acceleration: In Virtual Box, try setting Paravirtualization Interface to None or Legacy.

Step 3. Modify the VMX (VMware) or VBOX (VirtualBox) Configuration

👉 For VMware:

• Power off the virtual machine.

• Locate the .vmx file.
• Open the file in a text editor and add the following lines:

Save the file and restart the VM.

👉 For VirtualBox:

• Add the following command using the command prompt:

• Remember to replace VMware with your actual virtual machine name.

Step 4. Check Boot Arguments (for macOS Guest OS)

If you are running macOS as a guest OS, try adding boot flags:

• Start the VM.
• When the boot loader appears, enter:

• Press Enter and see if the system boots.

Step 5. Update or Reinstall the Guest OS

If the guest operating system is corrupt or incompatible, try reinstalling it with the latest version. Also, make sure you are using a compatible version of VMware, VirtualBox, or other virtualization software.

Step 6. Check Kernel Panics and Logs

If the VM crashes immediately, check the logs:

For VMware: Open the .log file in the VM folder.

For VirtualBox: Use the following command:

Protect Your Important Data Using an Efficient Backup Tool

When the CPU has been disabled by Guest OS error occurs, which can lead to potential data loss or corruption. So, for the safety of your data, we recommend you to use AOMEI Cyber Backup, a professional VM backup software designed to keep your data safe.

When you use AOMEI Cyber Backup, you can enjoy:

Centralized Management: It provides a centralized console for managing backups across multiple ESXi hosts, making it easy to monitor and maintain your backup tasks.
Incremental Backup: You can create a VMware incremental backup, saving only the changed made since the last backup, which can reduce storage space and speeds up the backup process.
Automate VMware Backup: It automates VM backup tasks, provides continuous VM protection, and reduces human error.
Agentless Backup: Backing up VMs at the host level eliminates the need to install an agent on each VM, reducing O&M costs.

How to Backup VMware VMs Easily

Step 1. In the AOMEI Cyber Backup, navigate to Source Device > VMware > + Add VMware Device, then enter Device Information and User Information.

Step 2. Go to Backup Task > + Create New Task, then set up Task Name, Backup Type, Device, Target, Archive, and Schedule.

• Backup Type: Select VMware ESXi Backup as the Backup Type.
• Target: Select to backup to a local path or to a network path.
• Schedule: You can perform a full, differential, or incremental backup.

Step 3. Click Start Backup, select Add the schedule and start backup now, or Add the schedule only.

Conclusion

The CPU has been disabled by the guest operating system error is usually caused by CPU incompatibility, misconfiguration, or operating system-related issues. In going through the methods provided in this article can help you solve the problem.