Undertale developer 8-4, Ltd. has confirmed that a major issue is affecting the progress of players on Nintendo Switch.
A unwelcome surprise
The bug in question can lead to the permanent loss of your save data when you start-up the game. However, you can rest assured that a fix is in the works and will hopefully be made available soon. In the meantime, you may want to adhere to the developer’s advice in the embedded post below:
Quick notice for Switch Undertale owners: there is a bug that can lead to accidental loss of save data if you don't select a user when you startup the game. A fix has been submitted, but for now, please make sure you select a user! (Don't press B to back out of this screen!) pic.twitter.com/ldTxbdf3Xq
— UNDERTALE (@UnderTale) September 18, 2018
But luckily they acted quick;
The 1.11 patch for UNDERTALE for Nintendo Switch is now live! It fixes the bug involving user-selection mentioned here. https://t.co/ZEo9TXKdex
— UNDERTALE (@UnderTale) September 26, 2018
So update people, update!