Update Linux Subsystem on Windows (Ubuntu) to 16.04

Answer: YES. This wasn't possible before, but now you can now update to 16.04 - with a little bit of work and patience.

Step 1: Update Windows to build #14936 or greater. (As of 2016-10-06, this is on the Windows Insider "Fast Ring".) To check your build number, first press "Win+R" and then type "winver" and ENTER.

Step 2. Install or Upgrade Linux using one of these three options:

Option A: If you have not yet installed the Linux Subsystem, you can simply install it from "Add or Remove Windows Components" and it should install version 16.04 by default.

Option B: If you have already installed the Linux Subsystem and you want to keep your environment, you can update it to 16.04 by executing "do-release-upgrade" from bash.

Reference: https://msdn.microsoft.com/en-us/commandline/wsl/release_notes#build-14936

EDIT: The following "full reset" method does not appear to work:

> lxrun /uninstall /full
> lxrun /install
> lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 14.04.5 LTS
Release:        14.04
Codename:       trusty

There is a way now, but it's somewhat unsupported, and do read the caveats:

https://github.com/Microsoft/BashOnWindows/issues/482#issuecomment-274584657

Quote from the post by Whorfin:

sudo -S apt-get remove screen
sudo -S apt-mark hold procps strace
sudo -S env RELEASE_UPGRADER_NO_SCREEN=1 do-release-upgrade

Sometimes this works straightaway. Sometimes it breaks, requiring a retry as follows

sudo -S dpkg --configure -a
sudo -S env RELEASE_UPGRADER_NO_SCREEN=1 do-release-upgrade

Repeat until done and ready for next steps.

I had to answer a full-window prompt to "restart services"

On one system I had to review changes to /etc/default/rcS

On all systems so far I had to review a change which added the regular [non -security] distro to /etc/apt/apt.conf.d/50unattended-upgrades

...and miscellaneous saying "y" to continue etc

After all that, the following:

sudo -S rm /etc/apt/apt.conf.d/50unattended-upgrades.ucf-old
sudo -S dpkg --configure -a
sudo -S apt-get update
sudo -S apt-get upgrade
sudo -S apt-get dist-upgrade
sudo -S apt-get autoremove

And good to go!

An aside - before I knew all this, I did the upgrade w/o the apt hold, and broke ps.

Recovering required not only the advice from others, but one more shared library package, as libprocps.so.3 was missing.

So, recovering a system with broken ps looks like this:

wget http://mirrors.kernel.org/ubuntu/pool/main/p/procps/procps_3.3.9-1ubuntu2_amd64.deb
wget http://mirrors.kernel.org/ubuntu/pool/main/s/strace/strace_4.8-1ubuntu5_amd64.deb
wget http://mirrors.kernel.org/ubuntu/pool/main/p/procps/libprocps3_3.3.9-1ubuntu2_amd64.deb
sudo -S dpkg -i procps_3.3.9-1ubuntu2_amd64.deb
sudo -S dpkg -i strace_4.8-1ubuntu5_amd64.deb
sudo -S dpkg -i libprocps3_3.3.9-1ubuntu2_amd64.deb