Just got this message for a new system update a little while ago. It is not the same update that came with the eshop not accepting cards anymore as I have already
System Update 11.17.0-50U released : r/3dshacks
3DS Update 11.17.0 | All You Need to Know! - YouTube
How to Update Games & Access eShop - 11.3.0 CFW - Avoid 11.4 Update with ctr-httpwn- n3DS & o3DS - YouTube
Help] My 3DS won't boot after system update | GBAtemp.net - The Independent Video Game Community
3DS System Update 11.16.0-49 Is Now Live, Here Are The Full Patch Notes | Nintendo Life
New Nintendo 3ds with custom firmware for Sale in Hayward, CA - OfferUp
HOW TO CHECK IF MY CONSOLE HAS CFW OR LUMA3DS - 3DS FINALIZING SETUP (OLD VERSION) - YouTube
RUNNING THE BOOTNTR SELECTOR ON FIRMWARE 11.14 ~ NEW METHOD - Sthetix