Jets general manager Joe Douglas is about to dump one of his predecessor’s biggest mistakes.

The Jets have informed cornerback Trumaine Johnson they will be releasing him in the coming days, according to a source. Former GM Mike Maccagnan signed Johnson to a five-year, $72.5 million contract in 2018, a signing that turned out to be one of the worst in franchise history.

The Jets must make the release of Johnson official by March 20, when his $11 million salary becomes fully guaranteed for 2020.

Douglas likely will wait to make the transaction until the players’ association votes on the new collective bargaining agreement later this week. The Jets would be able to designate Johnson as a post-June 1 cut under a new CBA, which would lessen the salary cap hit this year. In that scenario, Johnson would carry a $4 million charge in dead money in 2020 and $8 million in 2021.

If there is not a new CBA, Johnson will count the full $12 million toward the salary cap in 2020 and the Jets would only save $3 million against the cap.

The release of Johnson has been expected for months. His signing has felt like a mistake almost from the beginning. The Jets handed him $34 million in guaranteed money when they signed him. He battled injuries, ineffective play, a penchant for terrible penalties and alienated two coaching staffs.

The 30-year-old missed five games in 2018 with a strained quadriceps and then was a healthy scratch in the final game of the season for repeated rules violations. The Jets hoped the arrival of Gregg Williams as defensive coordinator in 2019 would spark Johnson. Instead, the team wound up benching him in Week 2. He regained his starting spot two weeks later, but did not have much impact and then ended up missing the final nine games of the season with sprained ankles.

Johnson ended up playing 17 games with the Jets, notching five interceptions with one returned for a touchdown.