Rektcon (a wordplay on “retcon”) was a site-wide reset of the Duckverse roleplay timeline that took place on Jan. 26th, 2016.
The decision to hit the 'reset' button on the entire universe was agreed upon by several of the regular players who felt the previous timeline had run its course. In real time, the Duckverse RP had been running for roughly seven years (2009 to 2016) which meant many of the long-time players had characters who were stuck in a rut due to several years of irreversible history, much of which had grown stale. This also made it harder for new players to integrate because all of the long-time characters were already deeply entrenched in previous relationships and story-lines.
Depending on which roleplayers joined Duckverse before or after January 2016, their involvement with Rektcon varies. Some characters will have a pre and post-rektcon timeline history while others do not.
The timeline was reset during a particular story arc called Another Lifetime in which Negaduck and NegaMorgana conspired against Malicia Macawber by luring her into a trap. NegaMorg cast a powerful spell that required a deadly sacrifice in the form of Mal's life, and Negaduck would execute the killing blow.
Their betrayal was successful although it deviated from the original plan, because Negaduck immediately felt regret over killing his long-time partner in crime. He turned his rage on NegaMorgana by murdering her before time reset itself.
Time reversed itself to the 'present day' of the cartoon series and reset the status quo. Most, if not all characters lost their memories of the previous timeline as well as their connections and relationships to other characters.