The veteran was playing in the last game of his illustrious 17-year career, but Rovers were crushed by promoted Peterborough on the last day of the season.
Butler’s misfiring side suffered their ninth defeat in 12 as the were put to the sword at the Keepmoat.
Mo Eisa and Niall Mason put potent Posh two up inside eight minutes before Idris Kanu and Ricky Jade-Jones made it four before the break.
Tyreece John-Jules grabbed a mere consolation in stoppage time as Rovers’ season ended with a whimper.
“We spoke in the changing room before the game about signing James Coppinger off with a performance,” admitted Butler.
“To be fair, I think we let him down and that’s disappointing.
“We need players who are proud to wear the Doncaster Rovers’ shirt. For half of the season I don’t think we’ve had that.”
The hosts got off to the worst possible start as Eisa’s stunning strike left Louis Jones stranded in the sixth minute.
And it went from bad to worse for Butler’s charges when Mason nodded home his first league goal of the season from Joe Edwards’s delicious delivery.
Kanu put the game to bed as a contest in the 15th minute when he headed home Harrison Burrows’s cross – his second goal in three appearances.
Reece James had a great chance to pull one back as he was well kept out by Christy Pym.
Joe Wright was stretchered off after a clash of heads with Jade-Jones.
And the Posh youngster bagged his first league goal as he made it four before the break with a fine left-footed finish.
After the break Coppinger almost gave himself a fitting farewell as he rattled the crossbar with a free-kick.
John-Jules grabbed a late goal as Rovers’ season ended with a disappointing defeat.
Doncaster: Jones, Wright (Halliday, 29), Anderson, Butler (Blythe, 45), Horton, Smith, Greaves (Sims, 45), John-Jules, Coppinger (Williams, 82), James, Bogle (Gomes, 71). Unused substitutes: Bottomley, Amos.
Peterborough: Pym (Blackmore, 83), Kent (Nascimento, 75), Edwards, Mason, Ward (Blake-Tracy, 68), Reed (Barker, 83), Hamilton, Burrows, Kanu, Eisa, Jones (O’Connell, 83). Unused substitutes: Thompson, Beevers.
Referee: P Wright (Merseyside).
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