Oracle : Prerequisite check "CheckActiveFilesAndExecutables" failed ; OPatch failed with error code 73

While patching the oracle database, the patch apply failed with below error
Following executables are active : /opt/app/oracle_db/oracle/product/oracle_db/lib/libclntsh.so.11.1 UtilSession failed: Prerequisite check "CheckActiveFilesAndExecutables" failed. Log file location: /opt/app/oracle_db/oracle/product/oracle_db/cfgtoollogs/opatch/opatch2016-02-25_11-13-41AM_1.log
OPatch failed with error code 73
Cause :
Something is using the library , we need to find what is using it and kill it.
find the culprit using fuser
Solution :
oracle_db@sev2(174) oracle_db /opt/app/patches $ fuser /opt/app/oracle_db/oracle/product/oracle_db/lib/libclntsh.so.11.1  
/opt/app/oracle_db/oracle/product/oracle_db/lib/libclntsh.so.11.1: 118942m  

oracle_db@sev2(175) oracle_db /opt/app/patches  

$ ps -ef | grep 118942 oracle_db  95662  57918  0 11:15 pts/0    00:00:00 grep 118942 oracle_db 118942 118378  0 Jan21 ?        00:00:00 sqlplus -s              @/opt/app/oracle_db/backup/rman/common/info.sql  oracle_db oracle_db@sev2(176) oracle_db /opt/app/patches  

$ kill -9 118942

And then start the patch apply. Hope this resolves your problem