ORA-00439: feature not enabled: Real Application Clusters & ORA-01078

when convert single instance to RAC and found below Error

Before that modified '/tmp/pfile-rac' file use *.cluster_database=true to support RAC

SQL> startup pfile='/tmp/pfile-rac'

ORA-00439: feature not enabled: Real Application Clusters
ORA-01078: failure in processing system parameters

Because => An Oracle Home disabled RAC.

So, we should relink library to enable RAC on this Oracle Home

$ cd $ORACLE_HOME/rdbms/lib

$ make -f ins_rdbms.mk rac_on

$ make -f ins_rdbms.mk ioracle


and then start again .