Avamar: Proxy Upgrade fails with Error Deleting Proxy

The Proxy Deploy Management (PDM) tool fails to upgrade Avamar proxy from the old version (7.2) to tje new version (7.3), reporting the following error in the console:

Error deleting proxy

The upgrade requires that the proxy VM is powered on

The Deploy Management log (/usr/local/avamar/var/log/vcs/deploymentmanager.log) reports this error and indicates that proxy disks across multiple datastores caused the issue:

2017-02-03T05:57:24.229+0530 TRACE [pool-3-thread-6][ impl.ConnectionManagerService#   releaseSession]: Releasing connection manager session: id=...1dc854f2ba11
2017-02-03T05:57:24.229+0530 TRACE [pool-3-thread-6][ impl.ConnectionManagerService# waitForVcSession]: Requesting connection manager vsphere session
2017-02-03T05:57:24.299+0530 TRACE [pool-3-thread-6][ impl.ConnectionManagerService# waitForVcSession]: Acquired vsphere session: ...03d7372986e8
2017-02-03T05:57:24.329+0530 ERROR [pool-3-thread-6][                 domain.Update#  getUpdateParams]: Unsupported configuration (proxy disks over multiple datastores)
2017-02-03T05:57:26.351+0530 TRACE [pool-3-thread-6][             util.VcConnection#            close]: Logging out of VC session
2017-02-03T05:57:26.351+0530 TRACE [pool-3-thread-6][ impl.ConnectionManagerService#   releaseSession]: Releasing connection manager session: id=...03d7372986e8
2017-02-03T05:57:26.352+0530 ERROR [pool-3-thread-6][           worker.UpdateWorker#              run]: Error updating proxy
java.lang.NullPointerException
        at com.emc.avamar.vmware.deploymanager.domain.Update.update(Update.java:68)
        at com.emc.avamar.vmware.deploymanager.worker.UpdateWorker.run(UpdateWorker.java:139)
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
        at java.util.concurrent.FutureTask.run(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
        at java.lang.Thread.run(Unknown Source)
2017-02-03T05:57:26.352+0530 DEBUG [pool-3-thread-6][             worker.TaskWorker#teTaskDescription]: Updating task description:
2017-02-03T05:57:26.358+0530 INFO  [pool-3-thread-6][             worker.TaskWorker#    sendTaskError]: Sending fault com.emc.avamar.vmware.vcs.deploymanager.delete_proxy_fault

A sample of Avamar proxy disks located on different datastores:

Attached Disk  : [VMFS-Production-Tier2-12] proxydisk.vmdk
Attached Disk  : [VMFS-Production-Tier2-70] proxydisk_3.vmdk

Engage the vCenter administrator to do a Storage vMotion to a completely different datastore for that proxy Virtual Machine (VM_.