This error has really got me paranoid. I think I might just not pick up the game until Nintendo fixes this. By the way, Nintendo is aware of the issue according to this article: http://nintendoeverything.com/some-smash...u-systems/
Also apparently an update came out for the Wii U just recently which seems to have fixed some user's error but not everyone's according to this SmashBoards thread.
Anyways, in the meantime, I advise everyone to be cautious before powering off your system since people claim that Smash saves during random times (like during the main menu) and powering off may corrupt some data. Close out the software then power off from the Wii U main menu. I've been powering off from directly from Smash for a while now but mainly during the opening cutscenes before the actual start of the game which may explain why I haven't encountered the error yet. Kind of grateful the game cuts back to the main menu -> opening after being idle after a while now since that's usually when I want to stop playing anyways...
Also apparently an update came out for the Wii U just recently which seems to have fixed some user's error but not everyone's according to this SmashBoards thread.
Anyways, in the meantime, I advise everyone to be cautious before powering off your system since people claim that Smash saves during random times (like during the main menu) and powering off may corrupt some data. Close out the software then power off from the Wii U main menu. I've been powering off from directly from Smash for a while now but mainly during the opening cutscenes before the actual start of the game which may explain why I haven't encountered the error yet. Kind of grateful the game cuts back to the main menu -> opening after being idle after a while now since that's usually when I want to stop playing anyways...