incomplete recovery

Even though all of the datafiles might have been restored to the same SCN, still some of them might be left in 'fuzzy' state.
select substr(name,1,40),recover, fuzzy, to_char(checkpoint_change#) checkpoint_scn from v$datafile_header;
select file#,STATUS, FUZZY from v$datafile_header;

to ignore those files:
ALTER DATABASE DATAFILE [datafile name] OFFLINE DROP;
or if you need to open, use hidden parameter:
_allow_resetlogs_corruption=TRUE;
this will open the database even though it's inconsistent. the database then must be rebuilt using export/import.

Refs:
435201.1