The Wii U 5.5.2 system update was released on July 18, 2017. This was released in Europe, North America & Japan.
Official USA change-log:
- Further improvements to overall system stability and other minor adjustments have been made to enhance the user experience
VersionData title, ErrEula title, AOC Overlay App title and Internet Browser were updated.
The browser changes include an updated mvplayer.rpl, this fixes the latest browserhax.
In the ErrEula title a new error was added "The Miiverse service has ended. Miiverse and any software features that make use of Miiverse are now unavailable."