When Ubuntu 21.10 reached End-of-Life (EOL) on July 14, 2022, its package repositories were moved to archive.ubuntu.com. This creates a problem when trying to upgrade because the standard do-release-upgrade relies on accessing the original repositories. Here's how we can work around this on ARM-based systems like Raspberry Pi 4.

First, modify your sources.list to point to the old-releases repository:

sudo sed -i 's|http://.*archive.ubuntu.com|http://old-releases.ubuntu.com|g' /etc/apt/sources.list
sudo sed -i 's|http://.*security.ubuntu.com|http://old-releases.ubuntu.com|g' /etc/apt/sources.list

Update your package lists:

sudo apt update
sudo apt upgrade -y
sudo apt dist-upgrade -y

We need to modify the release upgrader configuration to allow upgrading from an EOL release:

sudo nano /etc/update-manager/release-upgrades

Change these lines:

Prompt=normal
AllowThirdParty=yes

Now run the upgrade with the -d flag to force development release detection:

sudo do-release-upgrade -d -f DistUpgradeViewGtk3

If you encounter "No new release found", try:

sudo do-release-upgrade -p

On Raspberry Pi, you might need to resolve held packages manually:

sudo apt-mark showhold
sudo apt-mark unhold package_name

For kernel-related issues, you may need to:

sudo apt install --reinstall linux-image-generic linux-headers-generic

After successful upgrade, verify your system:

lsb_release -a
uname -a
apt list --upgradeable

Remember to reconfigure any services that might have been affected by the upgrade, especially those that modified system configuration files.

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When Ubuntu 21.10 (Impish Indri) reached its End of Life (EOL) on July 14, 2022, package repositories were moved to old-releases.ubuntu.com. This creates a significant hurdle for Raspberry Pi users who need to upgrade to 22.04 LTS, especially when dealing with ARM64 architecture.

First, check your current system details:

lsb_release -a
uname -m

Backup critical configurations and data:

sudo tar -cvpzf /backup/ubuntu-backup.tar.gz --exclude=/backup --exclude=/proc \
--exclude=/tmp --exclude=/mnt --exclude=/dev --exclude=/sys --exclude=/run /

Edit your sources list to point to the old-releases archive:

sudo sed -i 's|http://.*archive.ubuntu.com|http://old-releases.ubuntu.com|g' /etc/apt/sources.list
sudo sed -i 's|http://.*security.ubuntu.com|http://old-releases.ubuntu.com|g' /etc/apt/sources.list

Update the package lists:

sudo apt update --allow-insecure-repositories
sudo apt upgrade --allow-downgrades

Install the update-manager-core package if missing:

sudo apt install update-manager-core

Edit the release upgrade configuration:

sudo nano /etc/update-manager/release-upgrades

Set Prompt=normal and save the file.

Initiate the upgrade process:

sudo do-release-upgrade -f DistUpgradeViewNonInteractive

After reboot, verify the upgrade:

cat /etc/os-release
apt list --upgradable

Clean up obsolete packages:

sudo apt autoremove --purge
sudo apt clean

If encountering package conflicts on Raspberry Pi:

sudo dpkg --configure -a
sudo apt install -f
sudo apt full-upgrade

For kernel-related issues, consider installing the Raspberry Pi foundation's kernel:

sudo apt install --reinstall linux-raspi

For headless servers, you can create an automated upgrade script:

#!/bin/bash
# Force upgrade from 21.10 to 22.04
sudo sed -i 's|http://.*archive.ubuntu.com|http://old-releases.ubuntu.com|g' /etc/apt/sources.list
sudo apt update --allow-insecure-repositories
sudo DEBIAN_FRONTEND=noninteractive apt upgrade -y
sudo do-release-upgrade -f DistUpgradeViewNonInteractive -q
sudo reboot