Devera, 26, made 31 appearances for the Robins this season and started in both legs of their play-off semi-final penalty shootout defeat to Brentford.
Fellow defender Chris Smith, who did not feature for the first team this season, and midfield trio Raffaele De Vita, Simon Ferry and Tommy Miller will also leave the County Ground.
Midfielder Alan McCormack is currently in talks with the Robins about his new contract, while goalkeeper Leigh Bedwell, defenders Aden Flint and Nathan Thompson and striker Miles Storey have accepted new deals.
- Sports & Recreation
- Raffaele De Vita