Sometimes vCenter loses track of the snapshots on a virtual machine and may show no snapshots when in fact there is one (or more) in place. If you look at the actual vmdk files on disk you will see “delta” files for each vmdk.
Also when you try to storage vMotion the VM you get an error like this one
The fix is quite simple:
1. Right click on the VM -> Snapshot -> Take Snapshot
2. Exit window and reopen it again. You’ll see a consolidation-helper snapshot like this one
3. Click on Delete All and click on close
Depending on how large the snapshot is it may take a while. Once done check the vmdk files again, the delta files should now be gone. Then try and storage vMotion the VM again.