oracle_common missing from Oracle Fusion Middleware Home MW_HOME
Oracle_Common (aka COMMON ORCALE_HOME ) contains the binary and library files required for Fusion Middleware Control (/em) and Java Required Files (JRF). It is created in the Middleware Home (MW_HOME) directory after we install Fusion Middleware Components such as SOA, Webcenter, UCM, or Identity Management (IdM).
There can be only one Oracle Common home within each Middleware Home. If you can’t find oracle_common directory in your Middleware Home directory then it means that you haven’t installed any Fusion Middleware components yet.
To know more about oracle_common click here or for basics on FMW check Atul’s post here