Posted by I was patching my 12.1.0.2 home installation to the latest patchset today, and got the following error:
C:\oracle\stage\22581007>opatch apply
Oracle Interim Patch Installer version 12.1.0.1.10
Copyright (c) 2016, Oracle Corporation. All rights reserved.
Oracle Home : C:\oracle\product\1210~1.2
Central Inventory : C:\Program Files\Oracle\Inventory
from : n/a
OPatch version : 12.1.0.1.10
OUI version : 12.1.0.2.0
Log file location : C:\oracle\product\1210~1.2\cfgtoollogs\opatch\22581007_Mar_31_2016_18_32_02\apply2016-03-31_18-32-01 PM_1.log
Unable to lock Central Inventory. OPatch will attempt to re-lock.
Do you want to proceed? [y|n]
My first thought was this was due probably to the fact that I’ve got countless installations on this laptop, some running, some stopped, etc etc.
Turns out to be a much simpler issue. When running OPatch on Windows, make sure you are running it with the “As Administrator”.
Simple 
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