Has anyone successfully upgraded 12.1.0.2 to 18.0.0 (specifically 18.4) on AIX 7.1 Power 64?

I've been trying to simply upgrade a single-instance non-CDB database to 18.4.  But everytime it errors out.  "catupgrd0.log" throws a couple ORA-01422 errors and then eventually exits out near the end of completion.

ERROR at line 1:

ORA-01422: exact fetch returns more than requested number of rows

ORA-06512: at "SYS.CDBVIEW_INTERNAL", line 199

ORA-06512: at "SYS.CDBVIEW_INTERNAL", line 64

ORA-06512: at "SYS.CDBVIEW", line 6

ORA-06512: at line 1

ERROR at line 1:

ORA-01422: exact fetch returns more than requested number of rows

ORA-06512: at "SYS.DBMS_STATS", line 39134

ORA-06512: at "SYS.DBMS_STATS", line 38422

ORA-06512: at "SYS.DBMS_STATS", line 37316

ORA-06512: at "SYS.DBMS_STATS", line 36453