If you have installed Oracle 11gR2, the OPatch version will be 220.127.116.11.6 by default. If you proceed to apply any latest patches of 18.104.22.168, you must upgrade the OPatch version as well. The following error will be displayed if you try to apply a higher update of the patch and if your OPatch version is lower:
OPatch version : 22.214.171.124.6 ....... ApplySession failed: Patch ID is null. System intact, OPatch will not attempt to restore the system OPatch failed with error code 73
From the logfile
/u01/home/oracle/product/11.2.0/db_1/cfgtoollogs/opatch/opatch2012-12-15_11-57-48AM.log, the following message will be shown:
INFO:Starting ApplySession at Sat Dec 15 11:57:49 IST 2012 INFO:Starting Apply Session at Sat Dec 15 11:57:49 IST ...