Cannot access external drive in Windows 10 Linux Subsystem bash
Solution 1:
So I found the problem, I had to unmount it first and the mount it again:
sudo umount /mnt/d
sudo mount -t drvfs D: /mnt/d
This happened because it wasn't the first time I had connected this USB drive. The first time WSL (Windows Linux Subsystem) recognized and mounted the device automatically. But then I unplugged it without "Safe Remove" and without unmounting it through the command line. So, next time I re-connected the disk D: appears to be mounted in /mnt/d but not properly.
Solution 2:
In my case, this was my first time trying to access the external drive on WSL. The solution that worked for me is from this SO post which I post below:
$ sudo mkdir /mnt/d
$ sudo mount -t drvfs D: /mnt/d
Notice I did not have to unmount it as WSL did not mount the unit when I connected it for the first time. To safetely unmount the unit:
$ sudo umount /mnt/d