However, at the start of the 2015–16 season, Compper suffered a knee injury that kept him out of the first team for months. After returning to training from injury in September, he was assigned to the reserve side in order to regain his fitness. On 4 October 2015, he made his first appearance since returning from injury in a 3–2 win over 1. FC Nürnberg. Following his return, Compper regained his first team place despite facing new competitions this season. He was given a handful of first team appearances until he suffered a muscle injury that kept him out for two weeks in December 2015. Compper scored on his return from injury two months later on 7 February 2016, in a 2–0 win over Eintracht Braunschweig. Compper later helped the club get promoted to the Bundesliga for the first time after beating Karlsruher SC 2–0 on 8 May 2016. At the end of the 2015–16 season, he had made a total of 23 appearances and scoring three times in all competitions.