User blog comment:Otakon7/Otakon7's Buddyfight Simulator/@comment-11806403-20140726050530/@comment-2234004-20140726131023

Do note the error message kicks in when either player has issues, so it might be your friend, not you.

Normally however, the issue happens when there is a problem with the deck, so it could be there is a card that is causing issues (so making a deck from scratch and saving it as default can help). Just give me your name and I'll check it out.

On a note though, even if you get the message the game might still work as I noticed it can happen if there is a lag between two players at the start of the game, but if you play a few cards, all works ok.

P.S. Make sure you're not using Internet Explorer.