Para instalar o UbuntuStudio-Meta e outros pacotes, o que é o PPA para que as chaves corretas sejam instaladas, etc.? Tudo o que vejo é o Ubuntu Archive Master & Chaves de assinatura automáticas. E eu recebo este erro:
An error occurred during the signature verification. The repository is not updated and the previous index files will be used.
GPG error: http://ppa.launchpad.net/ubuntu-desktop/ppa/ubuntu xenial InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 2CC98497A1231595
Failed to fetch http://ppa.launchpad.net/ubuntu-desk...nial/InRelease