RCONFIG – Cannot get SQLEngine

Problem: convert to rac from single instance using rconfig gives error

$ORACLE_HOME/bin/rconfig ConvertToRAC_AdminManaged.xml

oracle.sysman.assistants.util.sqlEngine.SQLFatalErrorException: Cannot get SQLEngine
Operation Failed. Refer logs at /opt/oracle/app/itdoracle/12c/cfgtoollogs/rconfig/rconfig_09_07_21_15_55_33.log for more details.

Cause: ORACLE_HOME was not set properly in xml file

          <n:SourceDBHome>/opt/oracle/ora12201</n:SourceDBHome>

          <n:TargetDBHome>/opt/oracle/ora12c</n:TargetDBHome>

Solution: source and target were on the same server so set it accordingly to new server

          <n:SourceDBHome>/opt/oracle/ora12201</n:SourceDBHome>

          <n:TargetDBHome>/opt/oracle/ora12201</n:TargetDBHome>