Unable to change WSL 2 to WSL 1. A version number could not be parsed

Question

I installed WSL using the command

wsl --install

This installed default Ubuntu using WSL 2. Now I find WSL 2 is slow for file access cross NTFS files. And I read the WSL 1 is faster for file IO when using Linux tools that needs to access NTFS files (i.e. /mnt/g for example, where G:\ is NTFS).

But I am not able to change the installed Ubuntu back to WSL 1. Here is what I tried in PowerShell:

C:\Windows\system32> wsl --set-default-version Ubuntu 1
A version number could not be parsed.

C:\Windows\system32> wsl -l -v
  NAME      STATE           VERSION
* Ubuntu    Stopped         2

C:\Windows\system32> wsl --set-default-version "Ubuntu" 1
A version number could not be parsed.

C:\Windows\system32> wsl --set-default-version 1
The operation completed successfully.

But it did not change:

C:\Windows\system32> wsl -l -v
  NAME      STATE           VERSION
* Ubuntu    Stopped         2

I also rebooted the PC. I am also running all the above inside powershell.exe as Admin.

I am running Windows 10 Professional, version 21H1 OS build 19043.1620.

Any suggestions how to change back to WSL 1, hopefully without having to remove current Ubuntu since I spend lots of time installing Linux software on it since then?

My assumption is that one can change an existing install Linux from WSL 2 to WSL 1. This is based on many reading on the net, for example from this link

Answer 1

I found the problem. So I can either delete my question or post the solution. I thought it might be useful to show what I did wrong as may be someone will do the same mistake and find this.

If not, I'll be happy to delete my question and answer.

My mistake was using the command

   wsl --set-default-version Ubuntu 1

It should have been this

   wsl --set-version Ubuntu 1

now it says

   Conversion in progress, this may take a few minutes...

Now it works.