Tentou atualizar antes e foi atingido por um erro adorável no final.
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 trusty 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/trusty/InRelease
W: Some index files failed to download. They have been ignored, or old ones used instead.