WSL2: upgrade from Ubuntu 18.04 to 20.04

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I was afraid for missing my files, configurations and much other staff that I had in Linux filesystem of WSL2 (Windows 10). But I had to upgrade because of compatibility with an application that I need. So, finally, I decided to upgrade the Ubuntu 18.04 that I installed in WSL2 to a newer version 20.04. Yes, I know that there is 22.04 available nowadays, but I wasn’t comfortable jumping to many versions.

I followed simple steps that I found at:

How To Upgrade Existing WSL/WSL2 Ubuntu 18.04 to 20.04

The steps in a nutshell were:

sudo apt update
sudo apt upgrade -y
sudo apt --purge autoremove
sudo apt install update-manager-core
sudo do-release-upgrade

When I answered all the questions and after stopping the WSL2 VM with:

# command that I ran from 'cmd.exe' (Windows console)
wsl --shutdown 

I had and issue rebooting, WSL2 didn’t boot and it gave this message:

wsl/usr/sbin/enter-systemd-namespace: line 10: /usr/sbin/daemonize: No such file or directory

I resolved the problem, shutting down the WSL and running the command:

wsl -u root -e bash --noprofile --norc

It gave me a root console where I could modify the file:

/usr/sbin/enter-systemd-namespace

specifically, in line 10, I changed:

/usr/sbin/daemonize
to
/usr/bin/daemonize

And when I accessed to WSL2 everything worked perfectly. I used to access WSL2 from Windows Terminal which uses the command:

C:\WINDOWS\system32\wsl.exe -d Ubuntu-18.04

But it has small issues with bybou, finally I changed this command to:

C:\WINDOWS\system32\bash.exe ~ -login

I love to use a console with byobu enabled when access the shell, but with my former command, the command ‘byobu-enable’ was ignored. I didn’t find why, in the end the solution was to change the command that I use for accessing Linux console (WSL2).

Likewise, I hope these notes can help someone.