In the following years, Adler continued to be the first choice goalkeeper until newly signed Bernd Leno took his place due to injuries. He had made 37 appearances in the 2008–09 season, 33 appearances in 2009–10 season, and 44 appearances in the 2010–11 season. Previously, Leverkusen wanted to renew his contract but Adler rejected those offers. In summer 2012, Adler left the club for a free transfer after twelve years with Leverkusen. He had only made 2 B team appearances during the 2011–12 season.