Oracle Message ORA-10549 - Cannot perform block media recovery using a read-only plugged-in backup datafile.

ERRORCannot perform block media recovery using a read-only plugged-in backup datafile.
CAUSEAn attempt was made to perform block media recovery using a backup of a read-only plugged-in datafile.
ACTIONReattempt block media recovery using a backup taken after the plugged-in datafile has been converted to read/write.