Lock can not be changed

[Wif]

Immer, wenn ich versuche die Art der Bildschirmsperre zu ändern, beendet sich der App Einstellungen. 

Whenever I try to change the type of screen lock, the app stops settings.

GT

[Emil]

Hi @Wif and welcome to the community.

As this is a international community I have translated your post in to English, please keep your future post in English.

I recommend that you reboot your device to safe mode to make sure that this behavior isn't caused by one of your downloaded apps as these will be temporary disabled in this mode.

I also recommend that you clear all credentials in your device in the security menu. To do so, go to: Settings > Lock screen & security > Clear credentials > Ok

Let me know how it goes.