passportJS: req.user is returning undefined

i have simple passport-facebook & google oauth application and it works but problem it is not serializing users properly i guess because when i log req.user it returns undefined. here is my code for facebook oauth

passport.serializeUser((user,done)=>{
  done(null,user.id)
})
passport.deserializeUser((id,done)=>{
   const user = User.findById(id)
   done(null, user)
})
 passport.use(new FacebookStrategy({
    clientID: process.env.FB_CLIENT_ID,
    clientSecret: process.env.FB_CLIENT_SECRET,
    callbackURL: "http://localhost:3000/auth/facebook/callback"
  },
  async (accessToken, refreshToken, profile, done) => {
  const user = await User.findOne({ userId: profile.id })
  if(user){
    console.log('existing user '+ user)
    return done(null,user)
  }else{
   const newuser = User.create({ username: profile.displayName,userId: profile.id });
   console.log(newuser.toString())
   done(null,newuser)
   }
 }))

and here is passport-google-oauth2

passport.serializeUser((user,done)=>{
   done(null,user.id)
})
passport.deserializeUser((id,done)=>{
    const user = User.findById(id)
    done(null, user)
 })
passport.use(new GoogleStrategy({
    clientID: process.env.GOOGLE_CLIENT_ID,
    clientSecret: process.env.GOOGLE_CLIENT_SECRET,
    callbackURL: "http://localhost:3000/auth/google/callback"
  },
  async (accessToken, refreshToken, profile, done) => {
     const user =await User.findOne({ userId: profile.id })
       if(user){
         console.log('existing user '+ user )
         return done(null,user)
       }else{
         const newuser = User.create({ username: profile.displayName,userId: 
 profile.id });
   console.log(newuser)
   done(null,newuser)
  }

}))

and here is route config

router.get('/facebook', passportFacebook.authenticate('facebook'));

router.get('/facebook/callback',passportFacebook.authenticate('facebook', { failureRedirect: '/auth/login' }),
 function(req, res) {
  res.redirect('/');
 });
 router.get('/google',
  passportGoogle.authenticate('google', { scope: 'profile' }));
  router.get('/google/callback',passportGoogle.authenticate('google', { 
  failureRedirect: '/auth/login' }),
  function(req, res) {
   res.redirect('/');
 });

so what is wrong with this code?

The problem is you don't await for user in deserializeUser.

const user = User.findById(id)

You need to use then or await result from User.findById. So your deserializeUser code should be

passport.deserializeUser(async (id,done) => {
    const user = await User.findById(id)
    done(null, user)
 })