ORA-65096: invalid common user or role name with pluggable database

Issue:
====

While creating database user we got :

ORA-65096: invalid common user or role name

Fix:
====

SQL> create user arup123 identified by "n3vertalL";
create user arup123 identified by "n3vertalL"
            *
ERROR at line 1:
ORA-65096: invalid common user or role name


SQL> create user TU123 identified by *******;
create user TU123 identified by "*******"
            *
ERROR at line 1:
ORA-65096: invalid common user or role name


SQL> show con_name

CON_NAME
------------------------------
CDB$ROOT
SQL> SELECT PDB FROM V$SERVICES;

PDB
------------------------------
PDBORCL
CDB$ROOT
CDB$ROOT
CDB$ROOT
CDB$ROOT

SQL>  alter session set container=PDBORCL;

Session altered.

SQL> SHOW CON_NAME

CON_NAME
------------------------------
PDBORCL
SQL> create user TU123 identified by *********;
create user TU123 identified by ********
                                *
ERROR at line 1:
ORA-01109: database not open


SQL> ALTER DATABASE OPEN;

Database altered.

SQL> create user TU123 identified by ********;

User created.


SQL> GRANT CONNECT, RESOURCE, DBA TO TU123;

Grant succeeded.