OPatch failed with error code 104 when using OPATCH

Possible reasons for this error could be either a  missing oraInst.loc file or permission issues with oraInst.loc file, oraInst.loc located in in /var/opt/oracle  directory on unix platform. Ensure Oracle user have  read/write priviligies on orainst.loc file as well as on the actual path of orainventory location.

 if you could not fix the issue and if you know the inventory location you may want try following solution

"You would hardcode the orainventory location in Opatch apply command "

ex :opatch apply -invPtrLoc /full/path/oraInst.loc

 Here  invPtrLoc is a Opatch Switch .