You have more than one storage device with a FC 26 profile.

I am playing on Switch 2 and I have just been hit with the error message. It appears every time I launch the game and cannot be bypassed. Hitting Ok just displays the message again.

I do not have an additional storage device. I have no memory card inserted, just the internal storage.

I see that I am far from the first person to have this issue. Game is more expensive than ever and I can't even play it!