To prevent concurrent changes to critical virtual machine files, locks are placed on these files.
In certain circumstances, these locks may not be released. VMware snapshot deletion and consolidation processes will fail if the locks are not released.
You will see the following error in the vSphere environment:
Unable to access a file <filename> since it is locked
A couple of the identified causes are:
For cases where the hot-added disk has not been unmounted:
For cases where the ESXi host has failed to remove the lock, the management service on the host will need to be restarted.