SBC Debian apt update - The following signatures couldn't be verified because the public key is not available: NO_PUBKEY D34B9BFD90503A6B

[uptime1]

Downloaded 3CX SBC Debian ISO and installed it. Now want to perform typical Debian updates, logged in as root, but get this error. What's the fix?

apt update

Hit:1 http://deb.debian.org/debian buster InRelease

Hit:2 http://repo.3cx.com/3cx buster InRelease

Hit:3 http://deb.debian.org/debian buster-updates InRelease

Hit:4 http://security.debian.org buster/updates InRelease

Get:5 http://downloads-global.3cx.com/downloads/debian buster-testing InRelease

Err:5 http://downloads-global.3cx.com/downloads/debian buster-testing InRelease

The following signatures couldn't be verified because the public key is not available: NO_PUBKEY D34B9BFD90503A6B

Reading package lists... Done

W: GPG error: http://downloads-global.3cx.com/downloads/debian buster-testing InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY D34B9BFD90503A6B

E: The repository 'http://downloads-global.3cx.com/downloads/debian buster-testing InRelease' is not signed.

N: Updating from such a repository can't be done securely, and is therefore disabled by default.

N: See apt-secure(8) manpage for repository creation and user configuration details.

 

[uptime1]

Wonderful!

But SBC's running Debian 10 and earlier will NOT need to be upgraded to Debian 12 to be compatible with V20, correct?