Chesterfield have announced the signing of Danny Wilson as the new manager of the club.
The 55-year-old has managed a host of clubs, including Barnsley, Sheffield United, Swindon Town and Hartlepool United.
He parted ways with Barnsley in February.
Chesterfield currently sit eighteenth in the table, just two points above the relegation zone.
Chesterfield and Preston have both been charged by the Football Association for failing to ensure their players conducted themselves in an orderly fashion.
The charge relates to the Sky Bet League One play-off semi-final first leg between the two clubs at the Proact Stadium last week.
A testy beginning to the match finally boiled over in the 28th minute when Chesterfield winger Gary Roberts and Preston forward Paul Gallagher tangled.
Roberts appeared to grab his opponent by the throat as both players attempted to get up from the ground and a melee ensued involving men from both sides.
In addition, Preston assistant manager Glynn Snodin has been charged with misconduct.
Chesterfield have confirmed that manager Paul Cook has been released from his contract to join Portsmouth.
“I would like to thank Paul for the fine job he has done as manager of Chesterfield and wish him well for the future,” said chief executive Chris Turner.
“I could not have wished for a better working relationship than the one I have enjoyed with Paul over the last two-and-a-half-years and there is nobody more disappointed than me to see him leave.
“We will be looking to appoint Paul’s successor as soon as possible and the incoming manager will be in the enviable position of inheriting a strong squad.”
Cook, who joined Chesterfield from Accrington Stanley in October 2012, guided the Spireites to the League Two title in 2014 and the League One play-offs this season.
Assistant-manager Leam Richardson has also left the club. Richardson said: “I echo the manager’s sentiments and would like to thank everyone at the club, from the chairman and chief executive down, together with all the players, past and present. Thanks also to the fans for their tremendous support.”
Chesterfield FC will replay their Second Round Proper tie today after a breach of an FA rule meant their win against MK Dons was discounted.
The club played an "ineligible" player - Georg Margreitter on loan from Wolves - in their 1-0 win on 6th December. He didn't have written permission to play in the match.
The tie will played to a finish, with no further replay.
The FA said no further action will be taken against the club.
Chesterfield have achieved promotion to League One after a 2-0 win away at Midlands rivals Burton Albion.
Chesterfield have been beaten 3-1 by Peterborough at Wembley in the final of the Johnstone's Paint Trophy. 2 nil down from the first half, Eoin Doyle gave the Spirites hope of a comeback early in the second half but Brit Assombalonga's penalty 15 minutes from time sealed the win for Peterborough.