Some maintenance is going to make eShop code redemption impossible on three days soon. Nintendo of America announced that people won’t be able to shop as usual on three days in August and September, 2020. The first will keep people from claiming things today, which is August 24, 2020, while the other two will keep people from calling dibs on August 31, 2020 and September 14, 2020.
The outage will only apply to a very specific window on all three days. People who visit the eShop between 2pm-6pm PT/4pm-8pm CT/5pm-9pm ET won’t be able to enter any codes. This would apply both to the prepaid eShop codes that allow you to add credits to your wallet and to download codes for games or expansion passes that you might have picked up. Also, as noted by the official support page, this will apply to the Nintendo 3DS, Switch, and Wii U.
General eShop maintenance was also announced for the Nintendo Switch. Between 10pm-11pm PT on August 31, 2020, which is 12am-1am CT/1am-2am ET on September 1, 2020, people won’t be able to access the eShop at all due to regular maintenance.
Nintendo eShop codes for in-store credit or games can be found at various retailers like Amazon, Best Buy, GameStop, Target, and Walmart.