Welcome to Ubuntu 20.04 LTS (GNU/Linux 4.19.104-microsoft-standard x86_64)
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  System information as of Sun May 31 22:16:46 IST 2020

  System load:  0.22               Processes:             8
  Usage of /:   0.4% of 250.98GB   Users logged in:       0
  Memory usage: 1%                 IPv4 address for eth0: 172.19.7.170
  Swap usage:   0%

0 updates can be installed immediately.

This message is shown once once a day. To disable it please create the /home/kulfy/.hushlogin file. Well this is something new in Ubuntu app.

@EliahKagan Just installed WSL 2

I originally installed Ubuntu while WSL 1 was enabled. I ran wsl --set-default-version ubuntu 2 following MS docs but strangely encountered A version number could not be parsed.. Seems you need to be on WSL 2 while installing apps to enable --set-default-version option.

Reinstalled the app. Seems to be in WSL 2 now.

I have WSL2 on my Windows 10 system now as well.

@Kulfy --set-default-version sets the version of new distributions in WSL and doesn't accept an existing distribution as an operand. I think your command would've worked with --set-version in place of --set-default-version.

From wsl --help:

    --set-default-version <Version>
        Changes the default install version for new distributions.

    --set-version <Distro> <Version>
        Changes the version of the specified distribution.

When I ran it, but with --set-version, the command was accepted, but the attempt to actually change the WSL version on my existing distribution failed. I believe this was due to lack of disk space. My Windows 10 system is on a machine with a small system drive. Most of the software on it is on a separate drive, but I haven't managed to get any WSL systems to work if placed outside the system drive.

So I ended up doing the same thing you did. After uninstalling Ubuntu from the Microsoft Store and installing it again, it worked, and it's using WSL2.

Another benefit -- and this is why I took the 2004 update (I take recommended security updates immediately, but I usually wait at least a couple weeks to update my Windows system to new versions of Windows 10) -- is that Docker works on my Windows 10 system now.

@EliahKagan Oh. I missed that. Thanks for the info.

Apache2 also works seamlessly.

I hadn't tried running Apache2 in a WSL system. Did that not work in WSL1?

It did. But Windows Firewall used to block that.