Possible Duplicate:
How do I fix the GPG error “NO_PUBKEY”?
after sudo apt-get update
I get this error:
W: GPG error: http://archive.hivemind.me all Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 3C962022012520A0
Run the following in your terminal,
References: How do I fix the GPG error "NO_PUBKEY"?
You need to replace the key (3C962022...) with the one that is displayed in the error message in the terminal.
When you add a third-party repository, you should also add its key to your system. The public key is a string which identifies that certain repository. You can find some more information on this and how to add the key here.