dmesg showing only 5 lines?

Question

[ 0.010262] Microsoft 4.4.0-19041.1237-Microsoft 4.4.35
[ 0.078207] <3>init: (1) ERROR: ConfigInitializeCommon:665: Failed to mount /usr/lib/wsl/driver
[ 0.078211] : 19
[ 0.078372] <3>init: (1) ERROR: ConfigInitializeCommon:665: Failed to mount /usr/lib/wsl/lib:
[ 0.078375] 19

Answer 1

This seems to be a symptom of having WSL2 installed but Ubuntu (or whatever distro) has decided to be installed under WSL1 still.

You can verify this by typing (in PowerShell or Command Prompt):

wsl -l -v

Which will show if the distribution is under 1 still.

What's odd is that if you look at:

wsl --status

It may report that the default version is 2 but that doesn't appear to hold for systems that previously had WSL1 as I have repeatedly attempted to install Ubuntu-20.04 and Ubuntu-18.04 but they'd always show up with WSL1 (i.e. uname -r would output 4.4.0-19041...). You may be able to change the kernel version by using the wsl --set-version command but as I was going through a fresh install I found the following fixed the issue (the first command being most important despite wsl already claiming to default to 2):

wsl --set-default-version 2
wsl --install -d Ubuntu-20.04

After setup, I was greeted with the following in response to uname -r:
5.10.102.1-microsoft-standard-WSL2

And critically dmesg now shows the expected much more than 5 lines. And the /usr/lib/wsl/drivers /usr/lib/wsl/lib folders are correctly populated with content from C:\Windows\system32\lxss\lib etc.