After updating vCenter to 6.7U1, processing of all VMs fails with "Object reference not set to an instance of an object".
The issue is triggered by an update to the vSphere API version in vCenter 6.7 U1.
Create the following registry value under HKLM\SOFTWARE\Veeam\Veeam Backup and Replication key on the backup server:
Type: Multi-String Value (REG_MULTI_SZ)
Data: 6.7.1 = 6.7