Fixing NO_PUBKEY errors from Apt
I’ve been ignoring a problem updating Diodon (a great clipboard manager) whenever Ubuntu’s daily Update Manager tries to alert me of new software updates. I finally opened a shell prompt, ran apt-get update and got this error: signatures couldn't be verified because the public key is not available: NO_PUBKEY 751A20CF523884B2 Here’s how to fix any NO_PUBKEY error in two simple steps: $ gpg --recv-keys 751A20CF523884B2 gpg: requesting key 523884B2 from hkp server keys.