he following signatures couldn't be verified because the public key is not available: NO_PUBKEY EB3E94ADBE1229CF code example
Example 1: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 6494C6D6997C215E
Example 2: ubuntu 18.04 jenkins The following signatures couldn't be verified because the public key is not available:
Utils:
https://www.digitalocean.com/community/tutorials/how-to-install-jenkins-on-ubuntu-18-04
https://pkg.jenkins.io/debian-stable/
Solve the problem by adding this:
wget -q -O - https://pkg.jenkins.io/debian-stable/jenkins.io.key | sudo apt-key add -