How to find out if your WSL Ubuntu is running on WSL1 oder WSL2

In order to find out if your Ubuntu or other WSL linux installation is running on WSL1 or WSL2, open a Powershell and run

wsl --list -v

This will show you all WSL installations and the associated WSL versions:

PS C:\WINDOWS\system32> wsl --list -v
  NAME      STATE           VERSION
* Ubuntu    Running         1

As you can see, the Ubuntu VM is running WSL VERSION 1.

Go to the WSL2 installation page for instructions on how to upgrade to WSL2.