Veeam Backup & Replication 12.3 (build 12.3.0.310) has been recently released and it’s already available for download and fix some security issues.

But before upgrade to this version, it’s better to read carefully the related release notes and the upgrade guide.

Features no more available or changed from previous versions

Are you using File to Tape jobs? Consider the following: They have been re-engineered for scalability and are no longer free with Veeam Backup & Replication 12.2. You will have a grace period of 3 months following the upgrade to Veeam Backup & Replication 12.2, during which your existing jobs will not consume a license. For more information, see Instance Consumption for Object Storage Backup, File Backup, and File to Tape Jobs.

Do you have any jobs using the Transform previous backup chains into rollbacks option? This option has
been removed from the product since v 12.2, and such jobs are no longer supported. For more information, see Veeam KB 4390 (https://www.veeam.com/kb4390).

Note that the last known time-based retention policy is now applied to backups belonging to disabled backup jobs and to orphaned backups. You can use the Copy Backup functionality of Veeam Backup & Replication 12.3 to create a fully independent copy of the required backups, which will not be subject to the retention policy.

Are you using Veeam Backup Starter? This edition has been discontinued, so Veeam Backup &
Replication 12.2 will not accept such a license file. Please download a replacement license file from
the Customer Portal before upgrading.

Requirements

If you are upgrading to Veeam Backup & Replication 12.3 from previous versions, please review the upgrade checklist closely before performing the upgrade.

Veeam Backup & Replication 12.3 uses the same license file format introduced with version 10, so you
can use your existing version 10/11 license file to install version 12.3 (you don’t need the license file during the upgrade process).

Note the some of the new features of v 12.3 may require a Veeam Data Platform greater than the Foundation!

If you start from Veeam Backup & Replication 12.3, the resource requirements are different, for example for the Veeam Backup Server:

• CPU: x86-64 processor (minimum 4 cores recommended).
• Memory: 8 GB RAM plus 500 MB RAM for each concurrent job.
• Disk Space: 5 GB for product installation and 4.5 GB for Microsoft .NET Framework 4.7.2 installation. 10 GB per 100 VM for guest file system catalog folder (persistent data). Additional free disk space for Instant VM Recovery cache folder (non-persistent data, at least 100 GB recommended).
• Network: 1 Gbps or faster for on-site backup and replication, 1 Mbps or faster for off-site backup and replication.
• High latency and reasonably unstable WAN links are supported.

Same for the OS requirements that remain the same from v 12.1. Microsoft Windows Server 2025 has been added in v 12.3!

For the network ports, please note that starting with Veeam Backup Enterprise Manager 12, a new port (port 9405) is used for certificate communication between Enterprise Manager and Veeam Backup & Replication. Ensure that your firewalls are configured to take into account this new port to avoid communication issues between Enterprise Manager and Veeam Backup & Replication.

And you will need a lot of free space on you Veeam Server to perform the upgrade!

For the required space on disk, the minimum disk space is calculated on the flight after the system configuration check during the upgrade procedure. It is based on the list of required packages to be installed on the machine and usually is about 9 GB. Veeam recommends to provide the minimum disk space calculated during the system configuration check, but not less than 41.5 GB of disk space: 3 x ISO size (36.5 GB) in the selected installation path (for example, D:\VBR) plus 5 GB for the database operations on the system volume (for example, C:)..

Perform a Veeam Configuration backup, as described in Running Configuration Backups Manually.
Ensure you have configuration backup encryption enabled. Otherwise, stored credentials will not be
included in it.

Upgrade steps

To perform upgrade of Veeam Backup & Replication to version 12.3, you must be running version 11a (build 11.0.1.1261) or later on the supported operating system (refer to the System Requirements section of this document). For information on upgrade from earlier versions, see this Veeam KB article.

Are you using installations of Veeam Backup & Replication and Veeam Backup for Microsoft 365 on the
same machine? First upgrade Veeam Backup for Microsoft 365, second upgrade Veeam Backup &
Replication.

The main steps of the upgrade procedure are:

1. Download the latest ISO version since it will have the latest available cumulative patch built in.
2. Apply all Windows updates.
3. Disable all jobs and task:
   • Make sure the latest run for all existing jobs has been completed successfully. Rerun any failed jobs.
   • Ensure there are no running jobs, restore sessions, Instant Recovery sessions, or SureBackup jobs. Is recommend to do not stop running jobs and let them complete successfully.
   • Disable any periodic and backup copy jobs temporarily to prevent them from starting during the upgrade.
   • Disable CDP policies.
   • Ensure there are no active tasks from standalone (unmanaged) agents.
   • Ensure there are no active Veeam Disaster Recovery Orchestrator tasks.
4. Perform the configuration backup, as described in Running Configuration Backups Manually. Ensure you have configuration backup encryption enabled. Otherwise, stored credentials will not be included in it. For more information, see Creating Encrypted Configuration Backups.
5. If you are using an external database, perform a backup of the corresponding SQL Server configuration databases used by the backup server so that you can easily go back to the previous version in case of issues with the upgrade.
6. If you have Enterprise Manager, remember to update it before VBR!
7. If you use remote backup consoles, upgrade them manually using the product ISO file.
8. If Veeam Server is running on a VM consider to take a cold clone. Using VM snapshots could slow down the upgrade process (and will take a lot of time for the consolidation after the upgrade).
9. Mount the product ISO and use autorun or run the Setup.exe file. Click Upgrade in the Veeam Backup & Replication 12.3 splash screen.
10. Follow the upgrade wizard steps as outlined in the installation procedure above. Be sure to select the same database and instance used by the previous product version. For embedded PostgreSQL see also PostgreSQL connection issues during Veeam update.
11. Don’t select to upgrade the other compoments, otherwise you will be locked at the first login.
12. Plan your downtime properly… it takes time… a reboot to install some dependencies and a lot of time (and free space on C: because some components are there) for the upgrade. In a production environment with 1000 VMs it requires around of 40GB of free space and more than 30 minutes!
13. I suggest a final reboot to be sure that everything start correctly.
14. Upgrade all components. If some remote servers are unavailable at the time of the upgrade, you can run the Upgrade wizard at any time later from the main product menu. Note that jobs cannot use out-of-date product components until updated to the backup server version.
15. Re-enable the jobs after that all components are updated or jobs may not run correctly.
16. If you are using the Virtual Labs functionality, please open the settings of each virtual lab and click through the wizard to redeploy each virtual lab with the new proxy appliance version.

Please note that a reboot may be required after installing the update. Please plan accordingly.

Post upgrade

Are you using a customized AntivirusInfos.xml file? During the upgrade, Veeam Backup & Replication
will replace it with the default file. Make sure that you save your customized file at another path and
make necessary changes to the default file after the upgrade.

Note the the new version include PostgreSQL 15.10.1 (previous Veeam v12.2 versions use PostreSQL 15.8.1 versions). This will not be upgraded (if you have used the embedded database deployment). If you need to upgrade the database software, follow the Upgrade the embedded PostgreSQL in Veeam Backup 12.3 article.

And of course, the Windows Server operating system remain the same. If you plan to upgrade the OS, could be better build a new system and migrate the configuration (although an OS in-place upgrade is technically possible in several cases).