How to Fix Ubuntu 24.04 to 26.04 Upgrade Failed: PPA, Dependency & do-release-upgrade Errors (2026 Guide)

Why Ubuntu 24.04 to 26.04 Upgrades Fail

Upgrading Ubuntu from 24.04 LTS to 26.04 LTS should be straightforward — but a significant number of users hit a wall. Understanding why failures happen is the first step toward fixing them confidently.

The most common culprits are:

• Third-party PPAs that have not published packages compatible with Ubuntu 26.04, causing the upgrade calculator to report "an unresolvable problem occurred."
• Unmet or broken dependencies left over from previously installed packages that conflict with the new release's libraries.
• Interrupted upgrades that leave packages in a half-installed or half-configured state.
• Stale or unsigned repository sources that make do-release-upgrade abort.
• Timing: before Ubuntu 26.04.1 ships (expected August 2026), the LTS-to-LTS upgrade path requires the -d flag.

Pre-Upgrade Checklist

Skipping preparation is the biggest reason Ubuntu upgrades fail mid-way. Run through this checklist completely before upgrading.

1. Back up your data. Use Timeshift or rsync:

   sudo timeshift --create --comments "Pre-26.04-upgrade snapshot"

2. Apply all current updates:

   sudo apt update && sudo apt full-upgrade -y

3. Remove orphaned packages:

   sudo apt autoremove --purge -y

4. Fix broken packages now:

   sudo apt --fix-broken install

5. Ensure do-release-upgrade is available:

   sudo apt install update-manager-core -y

6. Confirm upgrade policy is set to LTS:

   cat /etc/update-manager/release-upgrades

   Verify Prompt=lts is present.

7. Free up disk space (at least 10 GB needed):

   df -h /
   sudo apt clean

8. Run inside tmux to survive connection drops:

   sudo apt install tmux -y
   tmux new -s upgrade

Fix: Removing PPAs Blocking the Upgrade

When do-release-upgrade encounters a PPA without 26.04-compatible packages, it reports:

An unresolvable problem occurred while calculating the upgrade.
This can be caused by:
 * Unofficial software packages not provided by Ubuntu

The fix: disable every PPA before upgrading, then re-add them afterwards if they gain 26.04 support.

Step 1 — List all active PPAs

grep -r "^deb" /etc/apt/sources.list /etc/apt/sources.list.d/ | grep -i ppa

Step 2 — Remove PPAs

sudo add-apt-repository --remove ppa:user/ppa-name

Step 3 — Revert packages with ppa-purge (recommended)

sudo apt install ppa-purge -y
sudo ppa-purge ppa:user/ppa-name

Repeat for every PPA identified. This reverts packages to the official Ubuntu archive versions.

Step 4 — Remove stale .list files manually if needed

ls /etc/apt/sources.list.d/
sudo rm /etc/apt/sources.list.d/problematic-ppa.list

Step 5 — Refresh and run the upgrade

sudo apt update && sudo apt full-upgrade -y

Before Ubuntu 26.04.1 (expected August 2026), use the -d flag:

sudo do-release-upgrade -d

After 26.04.1 ships:

sudo do-release-upgrade

Fix: Resolving Unmet Dependencies Mid-Upgrade

If the upgrade starts but stalls with dependency conflict errors, these usually involve packages from PPAs or manually installed .deb files pinned at incompatible versions.

Identify conflicting packages

sudo apt-get -f install
sudo dpkg --audit

Remove the conflicting package

sudo apt remove --purge conflicting-package-name
sudo apt autoremove -y

Force dependency resolution

sudo apt full-upgrade --fix-missing
sudo apt --fix-broken install

Check for held packages

sudo apt-mark showhold

Release held packages that are not intentionally pinned:

sudo apt-mark unhold package-name

After resolving dependencies, re-run sudo do-release-upgrade -d to resume.

Fix: Recovering a Half-Upgraded System

If your upgrade was interrupted, you may be left with a system that shows:

dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem.

Step 1 — Configure all half-installed packages

sudo dpkg --configure -a

Step 2 — Fix broken dependencies

sudo apt --fix-broken install
sudo apt install -f

Step 3 — Identify half-installed packages

dpkg -l | grep -E "^.H|^.U"

Reinstall each broken package:

sudo apt install --reinstall package-name

Step 4 — Remove stale lock files (only if no APT process is running)

sudo lsof /var/lib/dpkg/lock-frontend

If output is empty, remove stale locks:

sudo rm /var/lib/apt/lists/lock
sudo rm /var/cache/apt/archives/lock
sudo rm /var/lib/dpkg/lock
sudo rm /var/lib/dpkg/lock-frontend
sudo dpkg --configure -a

Step 5 — Review upgrade logs

cat /var/log/dist-upgrade/main.log
cat /var/log/dist-upgrade/apt.log

Step 6 — Continue the upgrade

sudo do-release-upgrade -d

Step 7 — Final cleanup after successful upgrade

sudo apt update && sudo apt full-upgrade -y
sudo apt autoremove --purge -y
sudo apt clean
lsb_release -a

If the system is too corrupted to continue, restore from your Timeshift snapshot or get expert Linux support from CloudHouse — our team can remotely diagnose and recover half-upgraded Ubuntu systems without data loss.

FAQ

Why does do-release-upgrade say "No new release found" on Ubuntu 24.04?

Before Ubuntu 26.04.1 ships (expected August 2026), the LTS-to-LTS upgrade is not advertised through the standard channel. Use the -d flag: sudo do-release-upgrade -d. Also confirm /etc/update-manager/release-upgrades contains Prompt=lts and not Prompt=never.

Is it safe to upgrade a production server from Ubuntu 24.04 to 26.04?

Yes, with proper preparation: take a full backup, remove all PPAs, resolve broken packages, and run inside a tmux session. For mission-critical servers, test on a staging replica first or contact CloudHouse for a managed upgrade.

Can I re-add my PPAs after upgrading to Ubuntu 26.04?

Yes. Once on 26.04, check whether the PPA has published packages for the Resolute Raccoon series. If supported, re-add with: sudo add-apt-repository ppa:user/ppa-name && sudo apt update.

What should I do if the upgrade downloads packages but fails during installation?

Run sudo dpkg --configure -a then sudo apt --fix-broken install. Check /var/log/dist-upgrade/main.log for the failing package. Remove it if safe and re-run sudo do-release-upgrade -d to resume.

How long does a Ubuntu 24.04 to 26.04 upgrade take?

On a 100 Mbps connection, expect 20–35 minutes for downloads and 15–25 minutes for installation — roughly 45–60 minutes total. Servers with many packages or slower disks may take longer.