APT - ошибка с ключами

В какой то момент apt начал жаловаться на ключи: There is no public key....

W: There is no public key available for the following key IDs:
7638D0442B90D010
W: There is no public key available for the following key IDs:
7638D0442B90D010
W: There is no public key available for the following key IDs:
9D6D8F6BC857C906
W: There is no public key available for the following key IDs:
9D6D8F6BC857C906
W: There is no public key available for the following key IDs:
7638D0442B90D010

Решается установкой пакета с ключами
apt-get install debian-archive-keyring debian-keyring -y
Подробней в wiki