Like every hardware and software components, before apply a VMware vSphere upgrade or update you have to check all compatibility aspects. One is related to the backup software that can be critical because you may loose the capability to perform backup and/or restore.

Of course this apply also to “minor” update, like vSphere 8.0U3.

For Veeam Backup & Replication there is a specific Veeam KB (KB 2443) that provides information about compatibility between VMware vSphere and Veeam Backup & Replication.

And finally, some weeks after ESXi 8.0.3 become GA, there is an official support for vSphere 8.0U3 starting with Veeam Backup & Replication 12.1.2 (build 12.1.2.172)!

The good news is that you probably already have this build because was released some months ago (2024-06-13).

The “bad” news is that is only a Compatibility-level support, with some known issues described in KB4641: Veeam Backup & Replication 12.1.2 Compatibility with vSphere 8.0 U3.

Actually there are just two possible issues… one may happen if you use NSX (see the KB for more details).

The other is related to the automatic exclusion of vCLS VMs does not occur after upgrading to vSphere 8.0 U3. This automatic exclusion feature, first introduced in Veeam Backup & Replication 10, fails to function because vSphere 8.0 U3 changed the VM type identifier for vCLS VMs. This because the the entire vCLS architecture has changed with the introduction of the embedded model.

Workaround: Add the vCLS VMs to the Global VM Exclusions list to prevent the jobs from attempting to process them (or just exclude the vCLS folder, but this should be done at job level). _{Note: The vCLS VMs can only be seen by Veeam Backup & Replication and added to the Global VM Exclusion list after upgrading to vSphere 8.0 U3 (when at least there is one ESXi 8.0.3 managed by vCenter Server 8.0.3).}

Full feature support for vSphere 8.0.3 will come with Veeam Backup & Replication 12.2.