Celtic chiefs claim their failed pursuit of Eddie Howe broke down for reasons that were out of both "his and Celtic's control".
The former Bournemouth boss had long been considered the front-runner to replace Neil Lennon.
But 94 days after the Northern Irishman resigned, the Hoops are back at square one after seeing their move for Howe collapse.
The PA news agency understands Hoops chiefs have now been forced to turn their attention elsewhere after the Englishman was unable to secure the backroom team he wanted to take with him to Parkhead.
Howe was the clear favourite of the Hoops support to pick up the pieces of a disastrous campaign.
Lennon resigned in February with Old Firm rivals Rangers well on their way to stopping the Hoops' quest for a 10th successive Premiership title.
Club bosses insist they are now in advanced talks with another candidate and hope to make an appointment soon.
But the way the Howe saga has panned out is unlikely to appease the fans demanding change in the Parkhead boardroom.
And with just 53 days until Celtic return to action with a vital Champions League qualifier on August 20, there is no more time to waste.
The club confirmed the Howe deal is now dead in a statement.
"Following very positive and detailed discussions with Eddie Howe, with the belief that he would be an excellent candidate for the position of Celtic manager, we allowed time for the process, given he'd previously made it clear he was not looking to return to management until this summer at the earliest," it said.
"We can now confirm that Eddie will not be joining the club, for reasons outwith both his and Celtic's control.
"We wish Eddie success for the future.
"As part of the ongoing process we have engaged with a number of candidates.
"We fully appreciate our fans will be seeking clarity on this matter and we aim, very shortly, to announce the appointment of a manager with the quality and desire to take Celtic forward and bring further success to our supporters."
It was widely believed that the hold-up in Howe's appointment was due to Bournemouth being involved in the Championship play-offs, with Howe reportedly looking to bring first-team coaches Stephen Purches and Simon Weatherstone as well as the Cherries' technical director Richard Hughes to Glasgow.
It is understood Celtic were willing to accommodate Howe's requests.
But the former Burnley boss' move north of the border is now off due to him being unable to assemble the backroom staff he wanted.