Ubuntu 24.04 LTS remains fully supported, but Ubuntu 26.04 LTS ships the Linux 7.0 kernel and updated security defaults. This guide upgrades a live Ubuntu 24.04 server to Ubuntu 26.04 LTS in-place using do-release-upgrade, handling the auxiliary SSH daemon, configuration file conflicts, and obsolete package removal. By the end, you'll have a running Ubuntu 26.04 system with the kernel version confirmed.

Prepare for the Upgrade

1. Update the APT package index and upgrade all installed packages:

$ sudo apt update
$ sudo apt upgrade -y

2. Remove obsolete packages:

$ sudo apt autoremove -y

3. Install the upgrade manager:

$ sudo apt install update-manager-core -y

Open the Auxiliary SSH Port

The do-release-upgrade tool starts an auxiliary SSH daemon on port 1022. Opening this port prevents being locked out if the primary SSH connection drops during the upgrade.

$ sudo ufw allow 1022/tcp

Run the Upgrade

1. Launch the release upgrade tool:

$ sudo do-release-upgrade -d

2. Follow the interactive prompts:

• Confirm the upgrade to Ubuntu 26.04 LTS when prompted
• Allow the auxiliary SSH daemon to start on port 1022
• Accept any keyboard configuration dialogs
• When asked about configuration files, keep the local version
• Confirm removal of obsolete packages when prompted
• Reboot the server to complete the upgrade

Verify the Upgrade

1. Confirm the OS version:

$ cat /etc/os-release

The output shows VERSION_ID="26.04" and VERSION_CODENAME="resolute".

2. Verify the kernel version:

$ uname -r

The output shows kernel 7.0.0 or higher.

3. Remove the auxiliary SSH firewall rule:

$ sudo ufw delete allow 1022/tcp

Next Steps

Ubuntu 26.04 is running with the latest kernel. From here you can:

• Review and update any third-party APT repositories that reference the noble codename
• Install the LAMP or LEMP stack to start hosting web applications
• Harden the server with fail2ban and automatic security updates

For the full guide with additional tips, visit the original article on Vultr Docs.