SYS@testdb> show con_name
CON_NAME
------------------------------
CDB$ROOT
SYS@testdb> create user test identified by "abcd";
create user test identified by "abcd"
*
ERROR at line 1:
ORA-65096: invalid common user or role name
SYS@testdb> create user c##test identified by "abcd";
User created.
SYS@testdb> alter session set container=test_pdb;
Session altered.
SYS@testdb> create user test identified by "abcd";
User created.
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