When you replace the vCenter Server configured in Veeam Backup & Replication, you need to re-map MoRef ID of protected VMs to complete backup jobs successfully.
During the migration to a new vCenter or if an inventory change occurs in the vCenter, the virtual machine MoRef ID changes with the result of a failure of the backup job associated with the error:
Object with reference <vmname> was not found in the hierarchy cache
This article has been written for StarWind blog and can be found in this page. It covers the full procedure to replace the vCenter Server in your vSphere infrastructure without altering the backup chains.
Re-map MoRef IDs with vCenter Migration Utility
To replace the vCenter Server configured in Veeam Backup & Replication, you need to keep same MoRef IDs for all protected virtual machines. In vSphere 6.5 and 6.7, the Upgrade option available in Stage 1: Deploy appliance wizard takes care of migrating also the virtual machine's MoRef IDs.
If you can't perform a successfull migration using the VMware Migration utility or if the source vCenter Server is corrupted or failed, as a last resort the migration can be achieved using the vCenter Migration Utility available at Veeam website. Although is not officially supported by Veeam, this tool allows to re-map the MoRef ID's keeping the backup incremental chains intact.
If you use Cloud Connect repository, the tool cannot fix jobs targeting a Cloud Connect repository but an Active Full backup should be used instead.
After re-mapping the MoRef ID of protected VMs, the backup job is executed and completed successfully.
Read the full article on StarWind blog.