Erro NO_PUBKEY no Ubuntu/Debian

Mensagem de erro:

The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 978228591BD3A65C

Comando:

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 978228591BD3A65C

Fonte: https://www.vivaolinux.com.br/topico/Linux-Basico/erro-com-chave