3DS owners may have noticed an update today. The new update doesn't add much, but does fix key issues that arose from last month's 5.1.0-11U update.
According to Nintendo, today's update "resolves an issue that may prevent access to the System Settings or other features." Although I never experienced the problem, some users received an error during the system update and were then unable to access the System Settings, Nintendo eShop, or Game Notes. Nintendo says this update should fix that and prevent the error from happening again.
For those unaware of the previous update, it added a save transfer feature and streamlined the "Download Later" feature so that you're now able to download items in the background when your 3DS is in Sleep Mode.