How to reinstall vSphere Web Client plug-in for Veeam ...
https://www.veeam.com/kb184923.01.2014 · In Veeam Backup Enterprise Manager, go to the vCenter Servers section of the Configuration view. Select the vCenter server you need and click Check version. If a connection to vCenter server was a success, and the plug-in is installed in vSphere Web Client, the Remove link will become active. Click the link to uninstall the plug-in.
KB2136: vCenter Migration Utility - Veeam Software
https://www.veeam.com/kb213608.06.2016 · Veeam Backup & Replication tracks Virtual Machines in its jobs by their Managed Object Reference ID (MoRef ID), which will change when a VM is moved to another vCenter, a new vCenter Database is used, or the VM is removed and re-added to vCenter inventory. Solution The Migration Tool is available here.