The Premier League side will now have to bring in a new keeper ahead of the coming campaign.
The Pole has gone ahead with ankle surgery and will be out for most of the season.
Manager Steve Cooper said: “Vards unfortunately had a knock in the game against Villarreal. Fortunately he’s not going to be out for too long. We’re hoping he'll be back with us in and around the Germany camp, if not, just after that. There was a bit of a sigh of relief.
“Jakub, it’s really unfortunate, he had a very innocuous injury in training and it’s ended up being really serious. He’s had to have an operation on his ankle and he’s going to be out for a long time.
“It couldn’t be any more bad luck. He’s found himself in a tough situation. He did it on the day we flew to Evian, we trained before we travelled. I feel for the boy. I’ve heard some really good things about him, and how talented he is.
“We’ll support him. The club is very well set up in terms of how they support players. We’ll get him back as quickly as possible. I think it will be around six months.”