Cause: A datafile restore specified no target file name, but the database is not mounted. The database must be mounted when no target file name is specified, so that the target file name can be obtained from the control file. See the solution below.
Error solution: The restore conversation remains active. If you wish to restore datafiles without their target file names, then mount the database before continuing. Otherwise, a target file name must be specified on all datafile restoration calls.
Database version: Oracle 11g Release 2 (11.2)