devtrackers.gg
It’s a bug; we’re aware and working on a fix. As others have pointed out, this is a warning intended for [[Mastermind’s Acquisition]] or [[Karn, the Great Creator]].
Also, though it’s worded a little strongly, it doesn’t actually require you to have a sideboard. Hitting “Ok” on the screen shown saves the deck as normal.
Already? Mtga uses the magic online engine, which is quite old.
This is probably the result of technical debt already in placeIn my defense, the stack traces were super misleading! These developers are wizards :D
I never meant it as an insult or anything like that!
The truth is that you're always amassing tech debt, whether you make bad decisions or not.
However, this isn't tech debt, it's not a result of using the MTGO engine (our engine is new), and Mastermind's Acquisition isn't broken (you can play the card and choose the second mode without a sideboard).
#wotc_staff