Oracle Message ORA-08176 - consistent read failure; rollback data not available

ERRORconsistent read failure; rollback data not available
CAUSEEncountered data changed by an operation that does not generate rollback data : create index, direct load or discrete transaction.
ACTIONIn read/write transactions, retry the intended operation. Read only transactions must be restarted.

3807Error messages regarding rollback and undo segments