EXPDP ORA-39126 and ORA-01427

Dear,

I have received error ORA-39126 ORA-01427, in my Oracle 12.1.0.1, I can not run Expdp:

ORA-39126: Unexpected fatal worker error in KUPW $ WORKER.FETCH_XML_OBJECTS [INDEX: "STN". "IX_BUSCA_1"]

ORA-01427: Subquery of a single row returns more than one row

ORA-06512: em "SYS.DBMS_SYS_ERROR", line 95

ORA-06512: em "SYS.KUPW$WORKER", line 11014

----- PL/SQL Call Stack -----

  object      line  object

  handle    number  name

0x51443ed40     26217  package body SYS.KUPW$WORKER

0x51443ed40     11041  package body SYS.KUPW$WORKER

0x51443ed40     13189  package body SYS.KUPW$WORKER

0x51443ed40      3128  package body SYS.KUPW$WORKER

0x51443ed40     11737  package body SYS.KUPW$WORKER