See this (closed) issue.
Short version:
Roots doc say: alias vagrant in WSL to vagrant.exe
Vagrant docs say: Vagrant must be installed within the Linux distribution used with WSL. While the vagrant.exe executable provided by the Vagrant Windows installation is accessible from within the WSL, it will not function as expected.
If you follow the Vagrant docs, the “Cannot translate name. @ rb_sysopen” goes away. That being said, I couldn’t get it working under WSL. Many other problems happened.
If you checkout the latest commits from the github master branch, and install from DOS as admin, It works. Specifically, this commit: