After updating, restart the game to verify that online services are functioning. No save data changes are included, so your Grand Prix progress, coins, and custom setups will remain untouched.
If you haven't already, you can download the update by following these steps: mario kart 8 update 3.0.5 download
Mario Kart 8 Deluxe Update 3.0.5 – What You Need to Know & How to Download After updating, restart the game to verify that