Pokémon Sword and Shield's surprise trade feature is currently causing players' systems to crash and is even having some long-term effects regarding online play.
The online community in Pokémon Sword and Shield tends to be quite a friendly one. Out of the ordinary when it comes to online gaming, we know. Its more dedicated players even organized a worldwide event called Surprise Trade Christmas last year. Its purpose was to gift new players to the game on and around Christmas Day with a powerful or rare Pokémon as a welcome to the game.
There are always a few bad apples in any orchard though, and those bad apples are now ruining Sword and Shield's Surprise Trade feature for everyone else. Trainers have been reporting instances of Pokémon received via Surprise Trades crashing their games. Some have even struggled to access Sword and Shield's online features after the fact, reports Polygon.
The Pokémon responsible for the problems are malicious ones that have been added by hackers. The problem is, of course, that trainers using Surprise Trade cannot dictate which Pokémon comes their way, otherwise, it wouldn't be a surprise. That means anyone using the feature might end up with an unwanted hacked Pokémon on their roster, and the above error message might well appear.
Furthermore, as touched upon above, others have reported the hacked Pokémon preventing them from using Sword and Shield's multiplayer Y-com function. There have been around 60 reported cases of this happening thus far. However, considering the number of people playing Sword and Shield, and only a tiny percentage of those players accessing message boards discussing the problem, chances are other players have been affected without knowing how widespread the problem is.
As for advice on how to avoid your Switch being infected with a hacked Pokémon, all trainers can do right now is refrain from using Surprise Trade. Game Freak has been informed so chances are there's a patch on the way. Stay tuned to Game Freak and Sword and Shield's social media channels for any updates regarding the situation and a patch.
Source: Polygon