Opatch Prerequisite check "CheckActiveFilesAndExecutables" failed. The details are: Following executables are active : /u01/app/11.2.0/grid/lib/libclntsh.so.11.1

Opatch auto failed with error:

Prerequisite check "CheckActiveFilesAndExecutables" failed.
The details are:
Following executables are active :
/u01/app/11.2.0/grid/lib/libclntsh.so.11.1

OPatch failed with error code 73

Cause

This library is still being referenced by an active process:
/u01/app/11.2.0/grid/lib/libclntsh.so.11.1

This error during apply is indicative of the cause of the problem:

Prerequisite check "CheckActiveFilesAndExecutables" failed.
The details are:
Following executables are active :
/u01/app/11.2.0/grid/lib/libclntsh.so.11.1

Solution

As per opatch*.log, there are still processes using one of the files that is being patched:
Following executables are active :
/u01/app/11.2.0/grid/lib/libclntsh.so.11.1

ACTION PLAN
~~~~~~~~~~~
1. As 'root' user, identify process using this file/library:
  # fuser /u01/app/11.2.0/grid/lib/libclntsh.so.11.1
  # lsof /u01/app/11.2.0/grid/lib/libclntsh.so.11.1

2. You may shutdown application or kill process using above file/library before trying opatch again.
  # crsctl stop crs -f
  # fuser /u01/app/11.2.0/grid/lib/libclntsh.so.11.1
  # kill -9 <ospid of process identified above>