Error
Oracle gives error when user creation Oracle 12c version.
SQL Error: ORA-65096: invalid common user or role name 65096. 00000 - "invalid common user or role name" *Cause: An attempt was made to create a common user or role with a name that was not valid for common users or roles. In addition to the usual rules for user and role names, common user and role names must start with C## or c## and consist only of ASCII characters. *Action: Specify a valid common user or role name.
Solution
SQL> alter session set "_ORACLE_SCRIPT"=true; SQL> create user username identified by password;