Moving​‍​‌‍​‍‌​‍​‌‍​‍‌ from Red Hat Enterprise Linux RHEL 8 to RHEL 9 is an essential move for keeping the system secure, stable, and compatible with modern software ecosystems. With RHEL 9, users benefit from enhanced performance, increased automation capabilities, and an improved management experience, all of which are based on Red Hat’s reliable enterprise-grade foundation.

We will show you how to carry out the upgrade thoroughly, professionally, and safely in this manual. The Leapp utility is the instrument officially endorsed for in-place upgrades to different major RHEL versions, and thus the method we employ here. You can upgrade with ease, and your downtime will be limited if you understand each of the ​‍​‌‍​‍‌​‍​‌‍​‍‌steps.

Step 1: Remove Temporary Leapp Directory

  • If this system was previously upgraded from RHEL 7 to RHEL 8, you must remove any remnants of the temporary Leapp upgrade directory to avoid conflicts.

sudo rm -rf /root/tmp_leapp_py3

  • This ensures that no leftover configuration or cached metadata interferes with the current upgrade.

Step 2: Verify RHEL Subscription

Before performing the upgrade, confirm that your RHEL subscription is active and properly attached. This step is critical because the upgrade process depends on Red Hat repositories.

sudo subscription-manager list –installed

  • If the subscription is inactive, re-register your system using:

sudo subscription-manager register

Step 3: Verify RHEL Repositories

Next, enable the necessary RHEL 8 repositories for BaseOS and AppStream, which are essential sources for upgrade packages.

sudo subscription-manager repos –enable rhel-8-for-x86_64-baseos-rpms –enable rhel-8-for-x86_64-appstream-rpms

This ensures that all the required packages for the upgrade are accessible from Red Hat’s official channels.

Step 4: Lock the System to RHEL 8.6

Before initiating the upgrade, it’s crucial to lock the system to RHEL 8.6, the officially supported source version for upgrading to RHEL 9. This guarantees a stable upgrade path.

sudo subscription-manager release –set 8.6

Locking to RHEL 8.6 ensures that you’re running a supported configuration and helps the Leapp tool perform compatibility checks accurately.

Step 5: Update Repositories and Install the Leapp Upgrade Tool

Update your package repositories and install the Leapp utility, which facilitates the in-place upgrade process.

sudo dnf update

sudo dnf install leapp-upgrade -y

Leapp analyzes system configurations, evaluates potential upgrade blockers, and safely transitions the OS from RHEL 8 to RHEL 9.

Step 6: Clear Version Locks and Adjust Firewall Configuration

Before running the upgrade, remove any version locks that may restrict package updates and ensure firewall drift prevention is disabled for smoother operation.

sudo dnf versionlock clear

sudo nano /etc/firewalld/firewalld.conf

In the configuration file, verify that AllowZoneDrifting=no is set appropriately to prevent unexpected behavior during network service reloading.

Step 7: Run Pre-Upgrade Assessment

The pre-upgrade check ensures that your system meets all prerequisites for a successful upgrade. It scans configurations, packages, repositories, and known compatibility issues.

sudo leapp preupgrade –target 9.0

After completion, review the generated report:

  • JSON log: /var/log/leapp/leapp-report.json
  • Text summary: /var/log/leapp/leapp-report.txt

If issues appear, address them before continuing.

Step 8: Perform the Upgrade and Reboot

  • Once the pre-upgrade report shows no critical errors, initiate the upgrade process:

sudo leapp upgrade –target 9.0

  • After completion, reboot the server to apply the new OS version:

reboot

  • The system will boot into RHEL 9, completing the upgrade successfully.

Post-Upgrade Verification

  • After rebooting, verify your RHEL version using:

cat /etc/redhat-release

You should see output confirming RHEL 9.0 (or later, depending on available updates). Also, check system services, applications, and network configurations to ensure smooth operation.

Conclusion

An​‍​‌‍​‍‌​‍​‌‍​‍‌ upgrade from RHEL 8 to RHEL 9 with the Leapp tool is a safe, supported, and straightforward process that keeps the system files and configurations intact and gives you the advantages of Red Hat’s new platform. If you proceed with the steps meticulously, especially repo verification, unchecking version locks, and executing pre-upgrade checks, you will be able to lessen the dangers and guarantee a stable switch.

We at ServerAdminz are proficient in the maintenance of secure Linux servers, patch automation, and OS lifecycle upgrades. Our specialists will work with you to the next stage of RHEL migrations planning, testing, and performing data loss-free and high-performance ​‍​‌‍​‍‌​‍​‌‍​‍‌scenarios.

If you need any assistance with RHEL upgrades, system recovery, or Linux performance optimization, contact ServerAdminz for professional support and seamless migration assistance.