PATH variable was pointing to 11.2.0.1 ORACLE_HOME rather than 11.2.0.2 ORACLE_HOME during the upgrade. Hence, the wrong version of sqlplus was invoked

 

PATH=/oracle/product/11.2.0/bin:/usr/sbin:/usr/kerberos/bin:/usr/local/bin:/bin:/usr/bin:/oracle/product/11.2.0/bin:/sbin:/usr/sbin:/home/oracle/bin:/home/oracle/bin:/oracle/product/11.2.0.2//bin:/usr/lib64/qt-3.3/bin:/usr/kerberos/bin:/usr/local/bin:/bin:/usr/bin:/home/oracle/bin:/usr/java

sqlplus banner follows (note that sqlplus release is 11.2.0.1.0 whereas the database version is 11.2.0.2.0)

 

$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.1.0 Production on Mon Aug 15 21:10:55 2011
Copyright (c) 1982, 2009, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Release 11.2.0.2.0 - 64bit Production
Connected to an idle instance.