Oracle Solution for Error ora-01598

Solution for Oracle Error ORA-01598

ORA-01598: rollback segment 'string' is not online

What triggered the Error:

Could have been taken offline before by DBA or cleaned up by SMON.

What should we do to fix it:

Check the status of rollback segment in undo$ or dba_rollback_segs to make sure the rollback segment is actually online.