Rangers boss Stuart McCall says he feels sorry for Gael Bigirimana, but admits he should never have been signed.
Chris Gunter will stay at Reading, after the club took up the option to extend his deal by another year.
Blackburn will not be offering new contracts to midfield pair David Dunn and Marcus Olsson and have released a further 16 players.
Dunn, 34, in his second spell at the club, made 24 appearances for Rovers this season, scoring four goals, while Swede Olsson featured on only nine occasions, although he started in the last three matches.
Blackburn-born Dunn made his debut for the club in the top flight in 1998 and moved on to Birmingham for a £5.5million fee in the summer of 2003, returning to Ewood Park in a £2.2million deal in January 2007.
Rovers, who finished two points shy of the play-offs, have also let William Beesley, Robbie Cotton, Ryan Edwards, Hugo Fernandez Molina, Timothy Payne, Deniz Pero, Aaron Tumwa and Matthew Urwin go.
Youth-team players Jordan Anderson, Thomas Brown, William Butterwick, Callum Harris, Thomas Paul, Yeray Torres Martinez, Ian Vicars and Brice Wassi have also been released.