Check if your CDB is set up for local undo

col PROPERTY_NAME format a20
col PROPERTY_VALUE format a20
col DESCRIPTION format a40
col LOCAL_UNDO_ENABLED format a20
select * from database_properties where property_name like '%UNDO%';

PROPERTY_NAME        PROPERTY_VALUE       DESCRIPTION
-------------------- -------------------- ----------------------------------------
LOCAL_UNDO_ENABLED   TRUE                 true if local undo is enabled