undo retention is in seconds. 43200 would be 12 hours x/3600
This will just reduce how long to retain undo not fix the problem.
select tablespace_name, (bytes/1024/1024) from DBA_DATA_FILES;
SELECT DISTINCT STATUS, SUM(BYTES), COUNT(*)
FROM DBA_UNDO_EXTENTS GROUP BY STATUS;
select * from v$parameter where rownum < 100 and name like '%undo%';
ALTER SYSTEM SET UNDO_RETENTION = 21600 scope=both;
ALTER TABLESPACE undotbs_01 ADD DATAFILE '/u01/oracle/rbdb1/undo0102.dbf' AUTOEXTEND ON NEXT 1M MAXSIZE UNLIMITED;
ALTER DATABASE DATAFILE '+<ASM>/<diskgroup>/datafile/undotbs1.292.696122207'
RESIZE 6G;
ALTER DATABASE DATAFILE '+<ASM>/<diskgroup>/datafile/undotbs1.292.696122207'
AUTOEXTEND ON NEXT 102400K
MAXSIZE 6G