res.send发送后无法设置标头

您好我有以下这种方法，我无法确定为什么我收到此错误

错误：发送后无法设置标头 . 在ServerResponse.json的ServerResponse.OutgoingMessage.setHeader（_http_outgoing.js：335：11）上的ServerResponse.header（/home/kwanso/Projects/myApp/Server/node_modules/express/lib/response.js:718:10） /home/kwanso/Projects/myApp/Server/node_modules/express/lib/response.js:246:10）在/home/kwanso/Projects/myApp/Server/app.js:92:11在Layer.handle [as handle_request]（/home/kwanso/Projects/myApp/Server/node_modules/express/lib/router/layer.js:95:5）下一步（/ home / kwanso / Projects / myApp / Server / node_modules / express / lib / router / route.js：131：13）完成（/home/kwanso/Projects/myApp/Server/node_modules/passport/lib/middleware/authenticate.js:243:13）/ home / kwanso / Projects / myApp /服务器/ node_modules / passport / lib / middleware / authenticate.js：250：15 at Authenticator.transformAuthInfo（/home/kwanso/Projects/myApp/Server/node_modules/passport/lib/authenticator.js:421:14） /home/kwanso/Projects/myApp/Server/node_modules/passport/lib/authenticator.js:443:5）/ home / kwanso / Projects / myApp / Se rver / node_modules / passport / lib / middleware / authenticate.js：247：22 at /home/kwanso/Projects/myApp/Server/node_modules/passport/lib/http/request.js:58:7 at pass（/ home / kwanso / Projects / myApp / Server / node_modules / passport / lib / authenticator.js：267：43）序列化（/home/kwanso/Projects/myApp/Server/node_modules/passport/lib/authenticator.js:276:7）在/home/kwanso/Projects/myApp/Server/app.js:97:3传递（/home/kwanso/Projects/myApp/Server/node_modules/passport/lib/authenticator.js:284:9） - 被叫来自/home/kwanso/Projects/myApp/Server/node_modules/express/lib/application.js:629:43(function EventEmitter.logerror）

我的方法如下：

passport.use(new LocalStrategy(
      function(username, password, done) {
        console.log("New Local Strategy");
        User.find({ email: username }, function (err, user) {
          console.log(user[0]._doc);
          if (err) { return done(err); }
          if (!user) { return done(null, false); }
          if (user[0]._doc.password != password) { return done(null, false); }
          console.log("sending");
          return done(null, user);
          console.log("sendt");
        });
        return done(null , false);
      }
    ));

    var isValidPassword = function(user, password){
      return true;
    }

    app.post('/login',
    passport.authenticate('local') ,
    function(req, res) {
      console.log("Back");
          res.send(req.user[0]);
    });

    passport.serializeUser(function(user, done) {
      console.log("Serialize User");
      done(null, user);
    });

    passport.deserializeUser(function(user, done) {
      console.log("De Serialize User");
      done(null, user);
    });

看起来它与在回调中的回调方法中调用res.send有关 . 这是一个问题吗？