VMware HCX
This is expected behavior due to the design of HCX migration functionality.
When "Enable seed checkpoint" is enabled, virtual machine disks created on the target datastore during a failed migration are retained, considering they may be reused during the next migration retry.
If these disks are no longer required during the next migration, they are automatically deleted after the migration completes.
If these disks have been manually deleted, this automatic deletion cannot be performed, and the error message is displayed.
This error message can be safely ignored in this scenario.
No issues will occur as long as the virtual machine migration is complete and no unnecessary disks remain.