The complete step-by-step guide for upgrading from Kubuntu 24.04 LTS to 26.04 LTS. Covers terminal and GUI methods, KDE configuration backup, known issues with Plasma 6.6, and what to check after the upgrade finishes.
-d flag until thenWhy Upgrade to Kubuntu 26.04?
If you are on Kubuntu 24.04 and things are working fine, the case for upgrading is straightforward. Kubuntu 26.04 ships KDE Plasma 6.6 – the most polished Plasma release to date, with a fully stable Wayland session, a new first-run setup wizard, improved HiDPI scaling, and a faster compositor. Under the hood, you get Linux kernel 7.0 with the NTSYNC gaming driver for better Windows game performance under Proton, and Qt 6.10.2 which brings measurable rendering improvements across all KDE applications. You also reset your support clock: Kubuntu 26.04 LTS is supported until April 2029, giving you three more years of security updates from a stable base. If you are still on Kubuntu 22.04, you are less than a year from end of life – upgrading now is the right move.
Which Upgrade Path Applies to You?
Not every Kubuntu version can upgrade directly to 26.04. The table below shows the supported paths. If your current version is not listed as a direct source, follow the step column first. If you would prefer a clean install over an in-place upgrade, the Kubuntu 26.04 download page has the official ISO links and SHA256 verification steps.
| Current Version | Direct to 26.04? | What to Do |
|---|---|---|
| Kubuntu 24.04 LTS | Yes | Follow this guide directly |
| Kubuntu 25.10 | Yes | Follow this guide directly |
| Kubuntu 22.04 LTS | No | Upgrade to 24.04 first, then to 26.04 |
| Kubuntu 23.10 / 25.04 (EOL) | No | These releases are end-of-life. Fresh install of 26.04 recommended |
| Kubuntu 20.04 LTS or older | No | Upgrade through each LTS in sequence, or do a fresh install |
Before You Upgrade – 5 Steps
Do not skip this section. These steps take less than 10 minutes and prevent the majority of problems that users run into during and after the upgrade.
The upgrade preserves your home directory, but hardware failures and power cuts do not care about timing. Back up anything important before starting. A full system snapshot is ideal if you are on a virtual machine.
This step matters more for Kubuntu than for any other flavor. KDE stores your panel layout, themes, widgets, keyboard shortcuts, and application settings in two directories: ~/.config and ~/.local/share. Old config files from Plasma 5 or earlier Plasma 6 versions can cause broken panels or visual glitches on first login after the upgrade. Run this before starting:
~/.config ~/.local/share
This creates a single compressed archive in your home folder. If anything breaks after the upgrade, you can restore from it or pick out specific files.
The upgrade tool will refuse to run if your system has pending updates. Run all four commands and reboot if the kernel was updated.
sudo apt upgrade
sudo apt dist-upgrade
sudo apt autoremove
Kubuntu 26.04 ships Linux kernel 7.0. NVIDIA driver series 470 and below are not compatible with it. Check your current version before proceeding.
If the result shows a version below 500 (for example 470.xx), upgrade your NVIDIA driver to 535 or newer before proceeding. Open System Settings, go to Driver Manager, and switch to a supported driver version.
Kubuntu 26.04 no longer installs the X11 Plasma session by default. Most applications continue to work through XWayland, a compatibility layer that runs X11 apps inside a Wayland session. However, some tools that interact directly with the X11 display – certain screen recorders, remote desktop clients, or older automation tools – may not function correctly. Check whether any software you depend on has known Wayland issues before upgrading. If you need the X11 session as a fallback, the plasma-session-x11 package is available in the Ubuntu archive after the upgrade, but it is unsupported by the Kubuntu team.
How to Upgrade via Terminal
This is the recommended method. It works on Desktop and any headless Kubuntu system, and gives you the most control over the process. The upgrade tool used is the same one Ubuntu uses – do-release-upgrade – which handles the Plasma packages alongside all base system packages.
The update-manager-core package provides do-release-upgrade. It is usually already present on Kubuntu 24.04, but this confirms it and installs it if missing.
Because the automatic LTS-to-LTS upgrade prompt is not yet enabled (it activates with 26.04.1 in August 2026), use the -d flag. This tells the tool to fetch the newly available release directly. Kubuntu 26.04 is a full production release – the -d flag does not mean unstable.
After 26.04.1 ships in August 2026, you can drop the -d flag and run sudo do-release-upgrade on its own.
The tool walks you through a series of prompts. Here is what to expect at each stage:
The tool checks for blockers, then shows a summary: how many packages will be upgraded, installed, and removed. Read this. Kubuntu upgrades typically touch several hundred KDE packages in addition to the base system. If anything looks unexpected, press N to cancel and investigate before continuing.
The tool downloads all required packages. Because Kubuntu includes the full KDE application suite, this step can involve more data than a base Ubuntu upgrade. Do not close the terminal or interrupt this process.
For system configuration files you have previously modified, the tool asks whether to keep your version or install the package maintainer’s version. If you have not customized the file, choose the maintainer’s version. If you have, keep yours and compare the two manually after the upgrade.
Near the end of the process, the upgrade tool may ask you to close open applications and will terminate the Plasma session to replace the desktop packages. Once all packages are installed, it prompts for a full system reboot. Choose yes – the system reboots into Kubuntu 26.04 with KDE Plasma 6.6.
When you run sudo do-release-upgrade -d on a remote Kubuntu system over SSH, the tool automatically opens a secondary SSH port (default: 1022) as a fallback in case your main connection drops. Before starting, open port 1022 through your firewall. If you use UFW: sudo ufw allow 1022/tcp. The tool will remind you and wait for confirmation before continuing.
A clean install gives you a fresh KDE Plasma 6.6 setup with no leftover configuration from older releases. Get the official ISO directly.
How to Upgrade via Software Updater (Desktop Only)
The graphical upgrade path on Kubuntu uses the same Software Updater backend as standard Ubuntu, not Plasma Discover. Discover handles application installs and updates, but the OS-level release upgrade runs through update-manager. There is one important caveat: Software Updater will not show a 26.04 upgrade prompt until Kubuntu 26.04.1 ships in August 2026. Until then, you need to launch it with a flag that tells it to check for newly available releases.
Software Updater opens and begins checking for updates. After applying any pending updates, it will show a banner: “Kubuntu 26.04 LTS is now available.” Click Upgrade to begin. The GUI walks you through the same process as the terminal method – with a visual progress bar and dialog boxes for configuration decisions. Total time: 40-70 minutes.
When the upgrade finishes, Software Updater will ask you to restart. Click Restart Now. Your system reboots into Kubuntu 26.04 LTS with KDE Plasma 6.6.
After the Upgrade – What to Check
Once the system reboots into Kubuntu 26.04, run through these checks to confirm everything is working correctly. The Plasma version check is specific to Kubuntu – it is not in the standard Ubuntu post-upgrade checklist.
The output should show Ubuntu 26.04 LTS and codename resolute.
Should report plasmashell 6.6.x. You can also check via System Settings – About This System.
Should report a 7.x kernel version.
sudo apt upgrade
A handful of packages often have updates available immediately after a release upgrade.
Known Issues and Fixes
These are the issues most likely to affect users upgrading from Kubuntu 24.04. All have known solutions or workarounds.
Cause: Configuration files from older Plasma versions can conflict with Plasma 6.6’s updated component structure. Panels may show as empty, widgets may fail to load, or the desktop may look different from how you left it.
Fix: If you backed up your config before upgrading (Step 2 above), you can restore specific files. For a clean reset without losing application data, rename your current config and let Plasma regenerate defaults: mv ~/.config/plasma-org.kde.plasma.desktop-appletsrc ~/.config/plasma-appletsrc.bak then log out and back in. Plasma will rebuild the panel from scratch.
Cause: Linux kernel 7.0 dropped support for NVIDIA driver series 470.x and older. If you upgraded without checking your driver version, you may boot to a black screen or a low-resolution fallback.
Fix: Switch to a TTY with Ctrl+Alt+F2, then install a compatible driver:
Reboot after installation. Driver 535 is also compatible if 550 is not available on your hardware.
Cause: The upgrade tool disables third-party PPAs during the upgrade to prevent conflicts. They are not deleted, just disabled. Some may also not yet have packages built for Ubuntu 26.04.
Fix: Open Discover or run software-properties-kde, go to the Other Software tab, and re-enable the PPAs you need. Run sudo apt update after. If a PPA fails, check whether the maintainer has released a 26.04-compatible version yet.
Cause: A documented compatibility issue between Snap’s audio confinement and Linux kernel versions 6.17 and 6.19 affects browsers and media apps installed as Snaps on Ubuntu/Kubuntu 26.04. System audio still works. This is a Snap-kernel interaction, not a Plasma or Wayland issue.
Workaround: If you encounter this after a kernel update, consider switching the affected apps to their Flatpak equivalents, which do not have this issue. Alternatively, hold the current kernel version with sudo apt-mark hold linux-image-$(uname -r) until a fix lands. A permanent fix is being tracked in the Ubuntu bug tracker.
If the upgrade is interrupted – by a power cut, a dropped SSH connection, or a package error – do not panic and do not try to reboot straight away. Open a terminal and run these two commands in order. They repair packages left in a half-installed state and resolve broken dependencies.
sudo apt install -f
Once both commands complete without errors, run the upgrade command again. The tool will pick up where it left off rather than starting from scratch.
Frequently Asked Questions
Can I upgrade directly from Kubuntu 22.04 to 26.04?
No. Kubuntu follows the same LTS upgrade path as Ubuntu. You cannot skip releases. You must first upgrade from Kubuntu 22.04 LTS to 24.04 LTS, then from 24.04 LTS to 26.04 LTS. Run sudo do-release-upgrade on your 22.04 system to reach 24.04, then repeat the process from there.
Why does do-release-upgrade say no new release found on my Kubuntu 24.04 system?
This is expected. The automatic LTS-to-LTS upgrade prompt is not enabled until the first point release, which for 26.04 is planned for around August 2026. To upgrade before then, run sudo do-release-upgrade -d to access the release directly. The -d flag means development or newly released, not unstable. Kubuntu 26.04 is a full production release.
Do I need to back up my KDE settings before upgrading?
Yes, and this matters more for Kubuntu than for any other Ubuntu flavor. KDE stores your desktop layout, panel configuration, themes, and shortcuts in ~/.config and ~/.local/share. Configuration files from older Plasma versions can sometimes cause broken panels or visual glitches after the upgrade. Run tar -czf ~/kde-config-backup.tar.gz ~/.config ~/.local/share before starting.
What happened to the X11 session in Kubuntu 26.04?
The Plasma X11 session is no longer installed by default in Kubuntu 26.04. Wayland is now the only fully supported session. If you need X11 for a specific legacy workflow, the plasma-session-x11 package is available in the Ubuntu archive, but it is not supported by the Kubuntu team. Most users will not notice the difference – XWayland handles compatibility for older X11 applications automatically inside the Wayland session.
Will my KDE themes, widgets, and customizations survive the upgrade?
Your configuration files are preserved during the upgrade. However, some themes or widgets built for older Plasma versions may not render correctly with Plasma 6.6. The Kubuntu team recommends backing up your ~/.config directory beforehand, then logging in fresh after the upgrade and re-applying customizations if anything looks wrong. Plasma’s settings migration handles most standard cases automatically.
How long does the upgrade from Kubuntu 24.04 to 26.04 take?
On a typical broadband connection, the full upgrade takes between 40 and 70 minutes including the download, package installation, and reboot. Kubuntu installs more packages than base Ubuntu because of the full KDE application suite, so it can run slightly longer than a standard Ubuntu upgrade. The process is unattended after the initial prompts, so you can leave it running.
Can I upgrade over SSH on a remote Kubuntu system?
Yes. When you run sudo do-release-upgrade -d on a remote system over SSH, the tool automatically opens a secondary SSH port (default: 1022) as a fallback in case your main connection drops during the upgrade. Allow port 1022 through your firewall before starting. If you use UFW, run sudo ufw allow 1022/tcp first. The tool will prompt you to confirm before continuing.
More Kubuntu 26.04 guides: Kubuntu 26.04 ISO Download · What’s New in Kubuntu 26.04 · Kubuntu 26.04 Wallpapers