ORA-12719: operation requires database is in RESTRICTED mode

Step by Step to Drop Database:-

[ordev@muthu01 env_bkp_10Mar13]$ sqlplus "/as sysdba"

SQL*Plus: Release 11.2.0.3.0 Production on Sat Mar 9 23:43:45 2013

Copyright (c) 1982, 2011, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> startup mount pfile=/home/ordev/env_bkp_10Mar13/initDEV011.ora
ORACLE instance started.

Total System Global Area 6263357440 bytes
Fixed Size                  2239976 bytes
Variable Size            4060086808 bytes
Database Buffers         2181038080 bytes
Redo Buffers               19992576 bytes
Database mounted.
SQL> drop database
  2  ;
drop database
*
ERROR at line 1:
ORA-12719: operation requires database is in RESTRICTED mode


SQL> shut immediate
ORA-01109: database not open


Database dismounted.
ORACLE instance shut down.
SQL> startup nomount pfile=/home/ordev/env_bkp_10Mar13/initDEV011.ora
ORACLE instance started.

Total System Global Area 6263357440 bytes
Fixed Size                  2239976 bytes
Variable Size            4060086808 bytes
Database Buffers         2181038080 bytes
Redo Buffers               19992576 bytes
SQL> alter database mount;

Database altered.

SQL> alter system enable restricted session;

System altered.

SQL> drop database;

Database dropped.

Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
With the Partitioning, Real Application Clusters, Oracle Label Security, OLAP,
Data Mining and Real Application Testing options
SQL>