Chris Kirchner has withdrawn his bid to buy Derby, leaving the League One club scrambling to find another buyer.
The American businessman had failed to reach a deadline on Friday to prove he could complete the takeover and County's immediate future is uncertain.
Kirchner had provided the English Football League with proof and sufficiency of funding.
Administrators Quantuma's press release reads: "The joint administrators can confirm that today, Mr Kirchner has withdrawn his offer to acquire the business and assets of The Club. We are aware that some will be concerned by this news, however, the joint administrators wish to reassure The Club's staff, players and supporters that they are continuing to actively engage with a growing number of interested parties, each of whom have a real willingness to complete a deal as soon as possible.
"The joint administrators would remind all stakeholders of the process in place for those parties who wish to acquire The Club. The joint administrators are running a competitive bidding process. Bids should be best and final and not contain any referential element. Clearly, any bid is subject to interested parties entering into an NDA, accessing the data room, and undertaking their own due diligence. Of the parties we are engaging with, some are more progressed in this process than others."
Kirchner had been named as Derby's preferred bidder in April and was given exclusivity over the process. Contract were exchanged last month, but details of the takeover's completion started to delay proceedings, with an original end date set for 31 May.
Derby's administrators will now talk to other interested parties in order to find a different buyer.
The club are due to play in League One next season after suffering relegation with manager Wayne Rooney, with County deducted 21 points during the 2021/22 campaign.