@marcinpraczko: To run WSL in a virtual machine, you need to configure the virtual machine to have nested virtualization support.

Here's how you can do that in VirtualBox: https://docs.oracle.com/en/virtualization/virtualbox/6.0/admin/nested-virt.html

@marcinpraczko

🖥️ How to Run WSL Inside Windows Running in VirtualBox
⚙️ Why It Fails by Default

WSL2 requires Hyper-V and virtualization support (nested virtualization).

When you install Windows inside VirtualBox, by default it cannot expose all virtualization extensions (Intel VT-x / AMD-V) needed for Hyper-V to work.

As a result, WSL2 errors out because it can’t start the lightweight VM backend.

🛠️ Possible Solutions

Enable Nested Virtualization (if supported)

On Intel CPUs:
VBoxManage modifyvm "Win11" --nested-hw-virt on

On AMD CPUs: VirtualBox nested support is limited and may not work reliably.

After enabling this, Hyper-V inside the guest OS may start working → WSL2 can run.

Use WSL1 Instead of WSL2

WSL1 doesn’t require virtualization — it runs as a compatibility layer.

To force install WSL1:
wsl --install --enable-wsl1
wsl --set-default-version 1

WSL1 has limited features (no full Linux kernel, no Docker integration), but works fine inside VirtualBox.

Switch to a Hyper-V–based Host VM

If you really need WSL2, the more stable approach is to use Hyper-V, VMware Workstation, or Parallels as the outer hypervisor.

VirtualBox has weaker nested virtualization support compared to these.

Alternative: Use Docker Desktop with WSL Backend Disabled

If your main goal is running containers, Docker Desktop can work with its own VM backend instead of WSL2 inside VirtualBox.

📌 Best Practice

If your host machine supports Hyper-V, run Windows directly or inside a Hyper-V VM, then enable WSL2.

Inside VirtualBox, the most reliable option is WSL1.

✅ In short:
WSL2 needs nested virtualization, which VirtualBox doesn’t fully support. You can either enable nested virtualization and hope it works (experimental), or more reliably, use WSL1 inside VirtualBox. For full WSL2 features, run Windows on bare metal or in a Hyper-V–based VM.

Thank you for all replies. I will test this solution and update this discussion.