Install gnupg and add OpenNMS repository GPG key sudo apt -y install gnupg sudo apt-key adv --fetch-keys https://debian.opennms.org/OPENNMS-GPG-KEY Add apt repository sudo apt -y install software-properties-common sudo add-apt-repository -s 'deb https://debian.opennms.org stable main' sudo apt update The message with conflicting distributions stable but got opennms-xx can be safely ignored. Installing the of Horizon Minion sudo apt -y install opennms-minion Disable the OpenNMS Horizon repository after installation to prevent unwanted upgrades when upgrading other packages on the server. After upgrade, Horizon requires manual steps to upgrade configuration files or migrate database schemas to a new version. For this reason, it is recommended to exclude the Horizon packages from update except when you are planning on performing an upgrade. sudo apt-mark hold opennms-minion Verify directory structure with the tree command sudo apt -y install tree tree /usr/share/minion -L 1 Directory structure after successful installation /usr/share/minion ├── bin ├── data -> /var/lib/minion/data ├── deploy -> /var/lib/minion/deploy ├── etc -> /etc/minion ├── lib ├── repositories └── system Enable Horizon Minion on system boot and start immediately sudo systemctl enable --now minion