Why is the Play button disabled in Vermintide 2?

I'm trying to play Vermintide 2 but the play button in-game is grayed out, so I can't click on it. I played one match earlier today, so I know it has been enabled in the past.

Image showing the "Quick Play" screen with an inactive "PLAY" button.

How can I play the game?


Solution 1:

You need to simply select a difficulty and the button will become enabled as per this source:

You have to click and actually select a specific difficulty