Hi All, I dropped the datafile undotbs1.dbf that blong to undo tablespace undotbs1 and added another datafile undotbs2.dbf . But now I see that v$recover_file shows undotbs1.df as a file to recover. so when I try to do this. it complains SQL> alter tablespace undotbs1 drop datafile '/lob1/undotbs01.dbf'; alter tablespace undotbs1 drop datafile '/lob1/undotbs01.dbf' * ERROR at line 1: ORA-03263: cannot drop the first file of tablespace UNDOTBS1 Can someone please suggest how do I synch it . thanks in advance Prasad