pg_restoring into a table with a not null column
Temporarily put a trigger on your target table to set default values:

CREATE FUNCTION override_null()
RETURNS trigger AS $$
BEGIN
  IF NEW.failed_port IS NULL THEN
    NEW.failed_port := 0;
  END IF;
  RETURN NEW;
END
$$ LANGUAGE 'plpgsql';

CREATE TRIGGER override_null_trigger
BEFORE INSERT ON c_a
FOR EACH ROW
EXECUTE PROCEDURE override_null();