And he swiftly found new employers in Scottish side Motherwell.
The 25-year-old brought an end to his disappointing Fratton Park career by finalising his release on Wednesday.
Main has struggled to break into Kenny Jackett’s side this season and departed with six months remaining on the deal he signed in July 2016.
That allowed the free agent to then link up with Motherwell, who he has joined on an initial 18-month deal.
And on a busy day at Fratton Park, while Main exited there were arrivals in Wolves duo Connor Ronan and Sylvain Deslandes on loan to the season’s end.
Main’s final Blues outing was a nine-minute cameo as a substitute against Bristol Rovers on New Year’s Day.
That was a ninth appearance of the season for the ex-Middlesborough man who has primarily been on the first-team fringes when fit.
It was Paul Cook who recruited him for an undisclosed fee from Doncaster, where he had fallen out of favour under Darren Ferguson.
Cook put the striker on a rigorous fitness plan to get him ready for the campaign, yet it would prove to be a frustrating maiden year for all concerned.
A combination of back and hamstring problems sidelined him from October, restricting his involvement to 14 games and five goals.
Had Cook remained, the likelihood is Main who have departed in the summer, yet Jackett arrived as boss.
He was the match-winner in the Checkatrade Trophy win at Charlton but that proved to be the last goal of a Blues career which consisted of 23 appearances and six goals.