Oracle Multi tenant Architecture ORA-20000 “12c 12.2.0.1.0” container Schema does not exist or insufficient privileges

I recently had to face such a problem. For those who give up, the answer is below 🙂

exec dbms_Stats.gather_schema_stats(‘TESTSCHEMA’);

ERROR at line 1:
ORA-20000: Schema ” TESTSCHEMA” does not exist or insufficient privileges
ORA-06512: at “SYS.DBMS_STATS”, line 38330
ORA-06512: at “SYS.DBMS_STATS”, line 38289
ORA-06512: at “SYS.DBMS_STATS”, line 8593
ORA-06512: at “SYS.DBMS_STATS”, line 38172
ORA-06512: at “SYS.DBMS_STATS”, line 38317
ORA-06512: at line 1

select dbms_stats.get_prefs(‘concurrent’) from dual;

exec dbms_stats.set_global_prefs(‘CONCURRENT’,’FALSE’);

SQL> exec dbms_Stats.gather_schema_stats(‘TESTSCHEMA’);
PL/SQL procedure successfully completed.