Stajner quits Hannover
The 33-year-old striker made up his mind to bring a premature end to his deal, which still had a year left to run, after helping the club avoid relegation to the second division this season.
Hannover agreed to release the player due to his eight years' service to the club, according to an announcement on their website.
Stajner made a total of 229 appearances for the Reds, scoring 42 goals including the equaliser in the 2-2 draw with Borussia Monchengladbach in the penultimate round of league matches - a goal which went a long way to securing the club's top-flight status.
With six goals, he was the club's second highest scorer in the recently-completed Bundesliga campaign.