ERROR;
This must be accepted explicitly before updates for this repository can be applied. See apt-secure(8) manpage for details
FIX:
sudo apt-get update --allow-releaseinfo-change
What does this do:
--allow-releaseinfo-change
Allow the update command to continue downloading data from
a repository which changed its information of the release
contained in the repository indicating e.g a new major
release. APT will fail at the update command for such
repositories until the change is confirmed to ensure the
user is prepared for the change. See also apt-secure(8)
for details on the concept and configuration