How to Upgrade FunOS 25.10 to FunOS 26.04 LTS

Upgrading your system ensures you get the latest features, improved performance, and long-term support. This guide will walk you step by step through upgrading FunOS 25.10 to FunOS 26.04 LTS, which is based on Ubuntu 26.04 LTS.

Pre-Upgrade Checklist

Before starting the upgrade process, make sure you are prepared:

• Backup your data
  Save important files to an external drive or cloud storage.
• Connect to a power source
  If you are using a laptop, plug it in to avoid interruptions.
• Check available disk space
  Make sure you have at least 10 GB of free space. You can check this by opening a terminal and running df -h /.

Step 1: Open a Terminal

You can open the Terminal in several ways:

• Click Menu → Terminal
• Click the Terminal icon in the tray
• Press Ctrl + Alt + T

Step 2: Update Current Packages

Before upgrading, ensure your system is fully up to date.

sudo apt update
sudo apt upgrade
sudo apt full-upgrade

Step 3: Reboot Your System

Restart your system to ensure all updates are properly applied.

sudo reboot now

Or:

• Click Menu → Log Out → Reboot

Step 4: Run the FunOS 25.10 Update Script

Before proceeding with the upgrade, run the FunOS 25.10 update script to apply any necessary system fixes.

rm -f funos-update
wget https://raw.githubusercontent.com/funos-linux/funos-updates/main/ubuntu/25.10/funos-update
sudo install -m 755 funos-update /usr/bin/funos-update
sudo funos-update
rm -f funos-update
sudo apt autoremove --purge

Step 5: Start the Upgrade Process

Run the following command to begin upgrading:

xscreensaver-command -exit
sudo do-release-upgrade

The xscreensaver-command -exit command aims to stop xscreensaver temporarily so that it does not interfere with the upgrade process.

⚠️ Troubleshooting:
If the output of the sudo do-release-upgrade command looks like this:

Checking for a new Ubuntu release
There is no development version of an LTS available.
To upgrade to the latest non-LTS development release 
set Prompt=normal in /etc/update-manager/release-upgrades.

It means the official upgrade path isn’t fully open on your mirror yet. You can force the upgrade by appending the -d flag. Run this command instead:

sudo do-release-upgrade -d

Step 6: Follow On-Screen Prompts

During the upgrade process, you will encounter several prompts. Here is how to handle them:

• Third-party sources disabled: You will see a notice that PPAs and third-party repositories have been disabled. Press Enter to acknowledge this (we will restore them later in Step 10).
• Restart services during package upgrades without asking?: Choose Yes so the upgrade can proceed smoothly in the background without constantly interrupting you.
• Modified configuration files: If prompted about replacing a configuration file, it is generally safest to choose Keep the local version currently installed (the default option). This preserves any custom system settings.
• Remove obsolete packages?: Type Y and press Enter to clean up old, unnecessary packages and free up disk space.
• General confirmations: For any other general prompts about package changes, type Y and press Enter.

Note: The entire process may take some time depending on your system performance and internet speed.

Step 7: Reboot After Upgrade

The upgrade tool will ask you to reboot at the end. Type Y and press Enter when prompted.

Step 8: Run the FunOS 26.04 Update Tool

After upgrading, run the FunOS update tool to apply system-specific improvements.

sudo rm -f /usr/bin/funos-update
sudo rm -rf /var/lib/funos-update
sudo rm -rf /tmp/funos-update
rm -f funos-update
wget https://raw.githubusercontent.com/funos-linux/funos-updates/main/ubuntu/26.04/funos-update
sudo install -m 755 funos-update /usr/bin/funos-update
sudo funos-update
rm -f funos-update
sudo apt autoremove --purge

What does this tool do?

• Adds new wallpapers to /opt/artwork/wallpaper
• Updates and enables the FunOS Plymouth theme
• Replaces volumeicon-alsa-legacy with volumeicon-alsa
• Installs Nitrogen
• Updates the Mozilla Team PPA
• Installs Dracut
• Cleans up unnecessary desktop entries

Step 9: Reload the Menu

To apply menu changes:

• Click Menu
• Click Reload menu

Step 10: Restore Third-Party Repositories

During the upgrade, the do-release-upgrade tool disables all third-party repositories. Manually restoring them can be complex, as you need to re-enable independent repositories (like Google Chrome) while removing and freshly re-adding OS-specific Launchpad PPAs.

To automate this entire process safely, we have provided a script that parses your repository files, automatically re-enables global repositories, and re-installs Launchpad PPAs for the new 26.04 release.

Run the script using the following commands:

wget https://raw.githubusercontent.com/funos-linux/funos-updates/main/ubuntu/26.04/restore-third-party-repos
sudo chmod +x restore-third-party-repos
sudo ./restore-third-party-repos
rm -f restore-third-party-repos

Once the script finishes restoring your repositories, run an upgrade to pull in any updated packages they might have for 26.04:

sudo apt upgrade

⚠️ Note:
Some third-party repositories may not yet support Ubuntu 26.04. If the script encounters an error while adding a specific PPA, you may need to wait until its developer officially supports Resolute.

Step 11: Verify the Upgrade

Check that your system is now running the new version:

lsb_release -a

You should see:

Description:    Ubuntu 26.04 LTS

Step 12: Final Reboot (Recommended)

For best stability, reboot once more:

sudo reboot now

Conclusion

You have successfully upgraded to FunOS 26.04 LTS. This version brings improved stability, updated packages, and long-term support.