Hi @Joulindo, welcome to the GitLab Community forum!
As others have noted, GitLab stopped building and releasing new packages for Ubuntu 16.04 prior to the 14.x release.
Here are your upgrade options:
Upgrade Options
Option A: Migrate GitLab from Ubuntu 16.04 server new Ubuntu 18/20.04 server
- Backup GitLab on 16.04 server
- Spin up new Ubuntu 18.04 or 20.04 server on seperate box
- Install GitLab on 18/20.04 box using same GitLab version installed on Ubuntu 16.04 box
- Copy backup to new 18/20.04 server
- Restore backup on new 18/20.04 server
Option B: In-place OS upgrade
- Upgrade to the latest version of available packages. OS upgrade will fail unless you’re running the latest version of 16.04 packages.
sudo apt-get dist-upgrade
- Initiate OS upgrade:
sudo do-release-upgrade
(ensure you’ll be available and attentive, this process will require user interaction and shouldn’t be stopped once it’s started) - Follow prompts, select to not change configuration if in doubt.
- Reboot
- Add GitLab package repository for your new OS version
curl https://packages.gitlab.com/install/repositories/gitlab/gitlab-ee/script.deb.sh | sudo bash
sudo apt update
(good additional resource: How To Upgrade to Ubuntu 18.04 Bionic Beaver | DigitalOcean)
If you encounter any problems, there are some troubleshooting steps here.