Unable to update to 2.387.2

We currently have Jenkins v2.387.1 running on an Ubuntu 16.04 LTS server. We cannot upgrade to 18.04 or later currently for business reasons.

Every time we try to update to v2.387.2 following the update guide, we get the following error:

Err:11 Debian Jenkins Packages binary/ Release.gpg
The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 5BA31D57EF5975CA

I have tried both of the following:

curl -fsSL https://pkg.jenkins.io/debian-stable/jenkins.io-2023.key | sudo tee \
  /usr/share/keyrings/jenkins-keyring.asc > /dev/null
echo deb [signed-by=/usr/share/keyrings/jenkins-keyring.asc] \
  https://pkg.jenkins.io/debian-stable binary/ | sudo tee \
  /etc/apt/sources.list.d/jenkins.list > /dev/null
  1. sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 5BA31D57EF5975CA

Both to no avail. I am no expert with Jenkins, but hopefully somebody here can chime in?

The Jenkins project does not support Jenkins on Ubuntu 16.04 or on Ubuntu 18.04.

Even with that, there was a mention in another thread somewhere that on those older Ubuntu versions they don’t accept ascii armored GPG keys. You could experiment with dearmoring that key, knowing that you’re working on your own in an area that the Jenkins project does not test.

Thank you for your response!
Unfortunately, this is what I expected was the issue.

If we are able to move the Jenkins server to Ubuntu 20.04 (pending approval) would we be able to target builds to run on Ubuntu 16.04 still? Or are we effectively stuck with 2.387.1 permanently?

Yes, I would expect that you could configure an agent to run on Ubuntu 16.04 while the controller runs on Ubuntu 20.04 or newer. That agent would be running on an operating system that the Jenkins project does not test or support, but that is a much smaller area of “unsupported” than if you are running the controller on Ubuntu 16.04.