HomeAutomation#switchPowerState with Fritz Dect 500 => code 500

[psychomom]

When trying to switch on a Fritz Dect 500 I'm getting a Response Code 500

Exception in thread "main" com.github.kaklakariada.fritzbox.http.HttpException: Request failed with response Response{protocol=http/1.1, code=500, message=Internal Server Error, url=https://192.168.178.1/webservices/homeautoswitch.lua?switchcmd=setswitchon&ain=13077%200171559&sid=3e0ee1169d88c622}
at com.github.kaklakariada.fritzbox.http.HttpTemplate.execute(HttpTemplate.java:132)
at com.github.kaklakariada.fritzbox.http.HttpTemplate.get(HttpTemplate.java:81)
at com.github.kaklakariada.fritzbox.http.HttpTemplate.get(HttpTemplate.java:71)
at com.github.kaklakariada.fritzbox.FritzBoxSession.getAutenticated(FritzBoxSession.java:90)
at com.github.kaklakariada.fritzbox.HomeAutomation.executeDeviceCommand(HomeAutomation.java:102)
at com.github.kaklakariada.fritzbox.HomeAutomation.executeParamCommand(HomeAutomation.java:82)
at com.github.kaklakariada.fritzbox.HomeAutomation.switchPowerState(HomeAutomation.java:114)