This article outlines important points to bear in mind...
In order to ensure protection is not affected when upgrading or replacing a vCenter, the vCenter database should be preserved. During the upgrade process, there is an option to preserve the existing database. Currently, detaching the database from one vCenter (virtual machine or appliance) and attaching it to another vCenter (virtual machine or appliance) is not supported -- as each vCenter also has its own UUID, which Zerto utilizes.
The vCenter database also contains UUIDs and Managed Object References for the VMware inventory that Zerto Virtual Replication utilizes, in order to interact with the environment. When a new database is created, the original values are replaced with new, different values and, as a result, Zerto Virtual Replication is unable to interact with the environment correctly.
If preservation of the vCenter database is not an option, then Zerto Virtual Replication will need to be re-installed on the site whose vCenter is being upgraded or replaced.
In this case, please follow the steps mentioned in Knowledge Base article entitled: Planning to Recover a Zerto Virtual Replication Installation after Recreating a vCenter Database.