[Answered ]-I am having troubles with a 404-error message from Django. It says "No location found matching the query"

The error message "No location found matching the query" suggests that the url pattern is correct, but there is no location with pk=1 in the database. You probably deleted it.

Try a different url e.g. /location/2/detail/ for a primary key that definitely exists.

You can find a primary key by doing something like Location.objects.first().id in the shell, or simply clicking on a location in the Django admin, and looking at the url.