unexpected ORA-00376: for offline undotbs

hi

I have a problem on 11.2.0.1 on AIX

undo tablespace already set to UNDOTBS1

undo management is AUTOMATIC

I performed the following steps

CREATE UNDO TABLESPACE undotbs3

ALTER SYSTEM SET UNDO_TABLESPACE=UNDOTBS3 SCOPE=BOTH;

alter tablespace UNDOTBS1 offline normal;

checked that UNDOTBS1 and its data files were offline

ran a series of very long running insert statements.

All correctly used UNDOTBS3

After all insert statements had completed and been committed the final steps include RENAME TABLE .

at this point there is an error

ORA-00376: file 3 cannot be read at this time

ORA-01110: data file 3: '/NBT6/d001/undotbs01.dbf'