My ubuntu doesn't proper update

Question

W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://deb.playonlinux.com precise InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 73F0D6E88E3D6C3A
W: Failed to fetch http://deb.playonlinux.com/dists/precise/InRelease  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 73F0D6E88E3D6C3A
W: Some index files failed to download. They have been ignored, or old ones used instead.

Answer 1

You should add "playonlinux" repository's public key:

wget -q "http://deb.playonlinux.com/public.gpg" -O- | sudo apt-key add -

after that run :

sudo apt update

from playonlinux download page.