Hi dnk9999,
There we are - the second datastore object is missing the Id attribute. This make it an incomplete object and hence the error.
Now this doesn‘t help your issue but at least we know the Update-VmfsDatastore cmdlet is probably okay.
The second object appears to be the target so let’s focus on that - now I would have thought every object would be assigned an Id because that’s how vCenter tracks stuff by assigning its own name to things.
Can you confirm that in the datastore objects you output what fields you blanked, if any? I would have expected the following to be present in your objects: DatacenterId, Datacenter, ParentFolderId, ParentFolder, DatastoreBrowserPath, Name, Id and Uid.
Also what vCenter privileges do you hold when running the cmdlet, i.e. do you have the Administrator role at the vCenter level?
Kind regards.