Manager Simon Grayson believes Leeds United will bounce back from their latest play-off heartache.
Luciano Becchio's second-half strike in Thursday's semi-final second leg with Millwall levelled the tie on aggregate.
However, Leeds suffered a fourth play-off defeat in five seasons after Jimmy Abdou equalised for the Lions on 74 minutes to secure a 2-1 aggregate victory for the London club.
Jermaine Beckford had missed a first-half penalty for the hosts.
"It's a bitter pill to swallow," said Grayson. "The players were outstanding tonight, we gave it a right go.
"We limited Millwall to very few chances and had the momentum, but probably just lacked a bit of quality in the final third to really test the goalkeeper.
"We're hugely disappointed. It was a great atmosphere and the fans deserve to go up, but the players can be proud of what they've achieved.
"We had plans for Championship football and League One football, we know where we are with players and budgets.
"So we'll get over it, start again and give it a real good go for automatic promotion next season."