Whether you play on it every day, or have put your 3DS to one side to gather dust as you obsess over your Switch, then shame on you for the time to take it in hand again has arrived.
For all 3DS and 2DS system, an all-new version update is available. Only don’t expect anything new as it is just more “further improvements to overall system stability and other minor adjustments have been made to enhance the user experience.” Which has been a recurring patch note that dates back as far as April 2015 as virtually every update had the same notes. (The only exception was in July 2015 when the patch notes was the same as what you see above in italics, but the July update also targeted system security as well.)
It is however a mandatory update as it prevent you from accessing the eShop, so don’t delay and download it today! You’ve not really got much of a choice otherwise.
Source: en-americas-support.nintendo.com