This past weekend, the public signing key that Google issues to sign and authenticate packages distributed through its Linux repositories has changed, resulting in users, perhaps yourself included, seeing various errors thrown up by the package manager.
If you’ve run an 'apt-update' since August 4 you may have got this error:
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: dl.google.com/linux/chrome/d… stable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6494C6D6997C215E
W: Failed to fetch dl.google.com/linux/chrome/d… The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 6494C6D6997C215E
W: Some index files failed to download. They have been ignored, or old ones used instead.
Google signs its packages with GPG keys so that you (and your package manager) can “verify product updates”. When a GPG expires, changes, or is otherwise missing from your system your package manager will display an error.
To fix this, open your terminal using :
Then run the following command:
wget -q -O - https://dl.google.com/linux/linux_signing_key.pub | sudo apt-key add -
You will be prompted for a password, there is no visual feedback so, please practice caution when entering.
Test if this worked by running anotehr 'apt-get' update.