Page not found (404)

Request Method: GET
Request URL: https://www.m1-hohenlockstedt.de/de/kalender/2017/4/22/vortraege-und-performances-von-discoteca-flaming-star-christine-lemke-hanne-loreck/
Raised by: app.schedule.views.ScheduleEventDetailView

Konnte keine Termin mit diesen Parametern finden.

You're seeing this error because you have DEBUG = True in your Django settings file. Change that to False, and Django will display a standard 404 page.