Before starting this process, my machine was running WSL 1. These are the steps I took to install and to start using WSL 2 side-by-side with WSL 1.

Install Windows 10 build 18917 or higher. This requires running Windows Update after joining the Windows Insider Program.

Restart the computer.

Enable the Virtual Machine Platform optional component:

dism.exe /online /enable-feature /featurename:Microsoft-Windows-Subsystem-Linux /all /norestart

dism.exe /online /enable-feature /featurename:VirtualMachinePlatform /all /norestart

Restart the computer.

Switch an existing, installed Linux distribution from WSL 1 to WSL 2. (We can later reverse this, if we want to, by running the command with a 1 instead of a 2.)

# list installed distributions
wsl --list 

# set an existing, installed distribution to use WSL 2
wsl --set-version Ubuntu 2

# check that the version switch worked
wsl --list --verbose

Test that it worked by pressing Windows + R and typing Ubuntu. A bash terminal will open. Try navigating to cd / and then typing ls -la to see the Linux root directory.

If you're using ConEmu, change Startup > Tasks > {Bash::bash} to wsl.exe ~ to make ConEmu's Bash command open to WSL at the user's directory. See also https://github.com/Maximus5/ConEmu/issues/1930

References

https://docs.microsoft.com/en-us/windows/wsl/wsl2-index

Title photo by Charles J Sharp - Own work, from Sharp Photography, sharpphotography, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=54619646