Wii U update version 4.0.3 out now, improves stability
Nintendo has released a new update for Wii U, bringing the firmware up to version 4.0.3. It’s primarily intended to improve system stability (as well as software compatibility).
You can find the official update notes from Nintendo below.
Version 4.0.3 U
Released: February 24, 2014
Further improvements to overall system stability and software compatibility
Thanks to LetsPlayWiiU for the tip.