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.

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.

xscreensaver-command -exit
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: Remove Unused Packages

Cleaning up unused packages helps prevent conflicts during the upgrade.

sudo apt autoremove --purge

Step 5: Start the Upgrade Process

Run the following command to begin upgrading:

xscreensaver-command -exit
sudo do-release-upgrade -d

Step 6: Follow On-Screen Prompts

During the upgrade:

• You may be asked to confirm package removals or changes
• Type Y and press Enter when prompted
• The process may take some time depending on your system and internet speed

Step 7: Reboot After Upgrade

Once the upgrade is complete, reboot your system:

sudo reboot now

Step 8: Run the FunOS 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

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

sudo 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: Re-enable Third-Party Repositories

During the upgrade, third-party repositories are disabled to prevent conflicts. You can re-enable them manually.

For .list repositories:

sudo sed -i 's/^# deb/deb/g' /etc/apt/sources.list.d/*.list

For .sources (deb822 format):

sudo sed -i 's/^Enabled: no/Enabled: yes/g' /etc/apt/sources.list.d/*.sources

Then update package lists:

sudo apt update

⚠️ Note:
Some repositories may not yet support FunOS 26.04. If you encounter errors, disable the problematic repository again.

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.