when I perform sudo add-apt-repository -y ppa:ethereum/ethereum this gives me an errors like,
gpg: keybox '/tmp/tmpy4v562r0/pubring.gpg' created gpg:
/tmp/tmpy4v562r0/trustdb.gpg: trustdb created gpg: key
1C52189C923F6CA9: public key "Launchpad PPA for Ethereum" imported
gpg: Total number processed: 1 gpg: imported: 1
**gpg: no valid OpenPGP data found.**
I tried many ways to solved but no luck.Please help me to solve this