After much fanfare, the big Queen performance featuring "American Idol" alum Adam Lambert at Sonisphere2012 isn't going to happen. The music festival has apparently been canceled.

Adam Lambert to Perform With Queen at U.K. Festival

"It is with very heavy hearts and much regret that we announce the cancellation of Sonisphere Knebworth 2012," Queen posted on its official site according to BBC.

Festival organizers are expected to release an official statement on Thursday.

Reports of Lambert and Queen's on-stage reunion (they previously performed together at the 2011 MTV Europe Music Awards) were finally confirmed by the festival's official bill followed by a tweet from the Idol alum on Feb. 20.

"As many suspected, I can finally confirm: I have been invited by Queen to sing one very special concert!" Lambert wrote. "Sorry to be coy about the details the past few weeks, but I made a promise to keep it under wraps as best I could. Gonna be a surreal night!"

Aside from Queen and Lambert's performance, the festival's bill also included Kiss -- who has also performed with Lambert during the "Idol" Season 8 finale -- Incubus, the Darkness and Evanescence.

Lambert's highly anticipated second full-length album "Trespassing" is due out May 15.