Tried to install a new system, using the raspbian buster image june 2019
first step would normally be:
sudo apt-get update sudo apt-get -yq upgrade
however, I got an error:
E: Repository 'http://security.debian.org/debian-security buster/updates InRelease' changed its 'Suite' value from 'testing' to 'stable' N: This must be accepted explicitly before updates for this repository can be applied. See apt-secure(8) manpage for details.
FIX, NOT tested, but explained by somebody on tweakers.net here (dutch):
sudo apt update
and answer '