How to Upgrade AlmaLinux 8 to AlmaLinux 9: A Practical Step-by-Step Guide

Why Upgrade?

AlmaLinux 9 brings numerous improvements over version 8 such as enhanced security features, updated software packages, better hardware support, and long-term stability aligned with RHEL 9. If you're running AlmaLinux 8 in production or for personal projects, upgrading ensures you have access to the latest advancements without reinstalling from scratch.

What You Need Before Starting

• A backup of your important data and server configurations.
• Root or sudo access to your AlmaLinux 8 system.
• Stable internet connection for package downloads.
• Familiarity with basic Linux commands.

Step 1: Update Your Current System

Before upgrading, ensure all current packages on AlmaLinux 8 are up-to-date.

sudo dnf clean all
sudo dnf -y update
sudo reboot

Reboot after updating to make sure new kernels or services are loaded.

Step 2: Install ELevate Tool

The AlmaLinux upgrade path from 8 to 9 leverages the ELevate tool by the AlmaLinux team. This tool simplifies migrating RPM-based distros between major versions while preserving data and some configs.

To install ELevate:

sudo dnf install -y https://repo.almalinux.org/elevate/elevate-release-latest.el8.noarch.rpm
sudo dnf install -y leapp-upgrade leapp-data-almalinux

Step 3: Perform Preupgrade Checks

Run pre-upgrade checks with:

sudo leapp preupgrade

This command analyzes system compatibility and generates a report at /var/log/leapp/leapp-report.txt.

Check the report carefully for any blockers like incompatible packages or services.

If there are warnings related to third-party repositories or unsupported software, consider resolving them before continuing. For example, disable or remove third-party repos temporarily:

sudo dnf repolist
sudo dnf config-manager --disable <thirdparty-repo>

Step 4: Start the Upgrade

Once your pre-upgrade report shows no major blockers:

sudo leapp upgrade

This will download and stage the necessary packages for the upgrade. Upon completion, you will be prompted to reboot your system.

Step 5: Reboot into AlmaLinux 9

After rebooting, your system should boot into AlmaLinux 9. Verify it with:

cat /etc/os-release

You should see output similar to:

NAME="AlmaLinux"
VERSION="9.x"
ID="almalinux"
...

Step 6: Post-Upgrade Cleanup

Run these commands to finalize package handling:

sudo dnf distro-sync -y
sudo dnf clean all

Also verify any critical services (web servers, databases) are running as expected.

Troubleshooting Tips

• If you face boot issues after rebooting post-upgrade, use kernel selection in GRUB menu to boot previous kernel & revert.
• Check logs at /var/log/leapp/leapp-upgrade.log and /var/log/messages.
• Disable custom kernels or drivers temporarily if incompatible.

Summary

Upgrading from AlmaLinux 8 to AlmaLinux 9 is straightforward when using the dedicated ELevate upgrade tool but requires careful preparation especially regarding third-party repositories and compatibility checks.

Backing up your system beforehand is essential — no upgrade process is risk-free!

With this guide, you're ready to take advantage of all the new features in AlmaLinux 9 without a fresh installation headache.

Feel free to ask if you want me to tailor this post with a specific tone or add advanced tips!