Attempting to rebalance VMware Horizon View linked-clones desktop pool datastore fails with: "Refit operation rebalance failed"

Problem

You attempt to migrate a linked-clone pool’s storage from one datastore to another by using the rebalance feature as outlined in the following KB:

Migrating linked clone pools to a different or new datastore (1028754)
https://kb.vmware.com/s/article/1028754

… but notice that the operation attempts the migration on a few desktops but fails with the error: Refit operation rebalance failed in the Events log of the linked-clones desktop pool:

Clicking on the ellipsis icon for the error for more information does not reveal additional information:

Navigating outside of the Events log of the linked-clones desktop pool then into the Inventory view and clicking on the ellipsis icon for the desktop in error displays the following message:

Apr 5, 2019 8:34:03 PM ADT: View Composer Invalid Parent VM Fault: View Composer Invalid Parent VM Fault: Selected snapshot on parent VM is not found on VC server

Pairing state:

Configured by:

Attempted theft by:

Solution

This error is usually caused by situations where the master image for the linked-clones pool no longer have the snapshots that the desktops being moved are associated with.  The rebalance operation requires access to the snapshots in order to re-clone the replicas (snapshots) to the new datastore so if they no longer exist then this error would be thrown.  In the case of the environment, the pool of 200 desktops had a mix of 5 different snapshots where only 1 of them was still available on the master image.  To view the linked-clones desktops and the associated snapshot that are being used, navigate to Inventory > Machines (View Composer Details) and review the Image tab:

If the snapshots have already been deleted then the way to remediate the error is to recompose all the snapshots with an existing snapshot on the master image or create a new one and recompose with it.  The rebalance operation should complete successfully once all the linked-clone pools are using a snapshot that exists.