Tried Software Updater Upgrade button for 16.04

I tried the Software Updater Upgrade button on the TX1 for 16.04 unsuccessfully.

Done it in 32 bit OS and 64 bit OS.

When booting, 16.04 shows up but:
Last error I got was:
tegra-xhci: failed to init firmware from filesystem: tegra21x_xusb_firmware

Anyone else got 16.04 on your TX1 successfully?

The Ubuntu-generated note about upgrade to 16.04 being available is unaware of the nVidia files to access hardware, including the kernel and its configuration or Tegra hardware changes. I would expect that upgrade path to fail, a significant amount of work would be required for this to succeed.