From 20.04 to 24.04 LTS: Safe Ubuntu Upgrade on DigitalOcean

The Problem

Upgrading legacy production servers is challenging in modern infrastructure, with many preferring containerization. However, sometimes inherited systems require direct OS upgrades, as demonstrated by a recent case involving an Ubuntu 20.04 server with outdated Nginx.

Directly upgrading from Ubuntu 20.04 to 24.04 LTS is not supported, necessitating a multi-step upgrade process to minimize risk and downtime. Outdated OS versions pose significant security risks, as they no longer receive critical security patches, potentially leading to breaches and data loss.

Key Insights

• Ubuntu 20.04 End of Life: Ubuntu 20.04 reached its end of standard support in April 2025.
• Incremental Upgrades: A staged upgrade path (20.04 → 22.10 → 23.04 → 23.10 → 24.04) mitigates risks compared to a direct leap.
• DigitalOcean Snapshots: Leveraging DigitalOcean snapshots and Floating IPs enables zero-downtime deployments and easy rollbacks.

Working Example

# Upgrade to Ubuntu 22.10
sudo sed -i 's|http://mirrors.digitalocean.com/ubuntu/|http://old-releases.ubuntu.com/ubuntu/|g' /etc/apt/sources.list && \
sudo sed -i 's|http://security.ubuntu.com/ubuntu|http://old-releases.ubuntu.com/ubuntu|g' /etc/apt/sources.list && \
sudo apt update && \
sudo apt upgrade -y && \
sudo apt dist-upgrade -y && \
sudo apt autoremove --purge -y && \
sudo apt install -y ubuntu-release-upgrader-core && \
sudo sed -i 's/kinetic/lunar/g' /etc/apt/sources.list && \
sudo apt update && \
sudo apt upgrade -y && \
sudo apt dist-upgrade -y && \
sudo apt full-upgrade -y && \
sudo apt autoremove --purge -y && \
echo -e "\nUpgrade complete! Rebooting now...\n" && \
sudo reboot

# Upgrade 23.04 → 23.10
sudo sed -i 's|http://old-releases.ubuntu.com/ubuntu|http://old-releases.ubuntu.com/ubuntu|g' /etc/apt/sources.list && \
sudo sed -i 's/lunar/mantic/g' /etc/apt/sources.list && \
sudo apt update && \
sudo apt upgrade -y && \
sudo apt dist-upgrade -y && \
sudo apt full-upgrade -y && \
sudo apt autoremove --purge -y && \
echo -e "\nUpgrade complete! Rebooting now...\n" && \
sudo reboot

# Upgrade 23.10 → 24.04 LTS
sudo sed -i 's|http://old-releases.ubuntu.com/ubuntu|http://archive.ubuntu.com/ubuntu|g' /etc/apt/sources.list && \
sudo sed -i 's/mantic/noble/g' /etc/apt/sources.list && \
sudo apt update && \
sudo apt upgrade -y && \
sudo apt dist-upgrade -y && \
sudo apt full-upgrade -y && \
sudo apt autoremove --purge -y && \
echo -e "\nUpgrade complete! Rebooting now...\n" && \
sudo reboot

Practical Applications

• Legacy System Maintenance: Organizations with older applications not easily containerized can use this method for OS upgrades.
• Pitfall: Skipping pre-upgrade backups can lead to significant data loss and prolonged downtime if issues arise during the upgrade process.

References:

• https://dev.to/tegos/from-20-to-24-lts-safe-way-to-upgrade-ubuntu-on-digitalocean-4gb