Recently while performing routine maintenance of our Ubuntu servers we discovered that the GnuPG build key used to sign MySQL downloadable packages has been updated. The previous GnuPG build key is set to expire on 2022-02-16.

W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: bionic InRelease: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 467B942D3A79BD29

The resolution for this is very simple, following the directions at MySQL:: Appendix A: Adding and Configuring the MySQL APT Repository Manually

$> sudo apt-get clean
$> sudo apt-key adv --keyserver --recv-keys 3A79BD29
$> sudo apt-get update

You’re now all set and your apt-get updates will work as normal.