Cannot read properties of undefined (reading '_id') using mongoDB

iv been trying to add post action to add tasks to db , Im using mongoDB as a db.

Here is my User model:

const mongoose = require('mongoose');

const Schema = mongoose.Schema;

const userSchema = new Schema({
    username: {
        type: String,
        required: true
    },
    password: {
        type: String,
        required: true
    }
})

module.exports = mongoose.model('User', userSchema);

And here is my Task model:

const mongoose = require('mongoose');

const Schema = mongoose.Schema;

const taskScheme = new Schema({
    description: {
        type: String,
        required: true
    },

    status: {
        type: String,
        required: true
    },

    userId: {
        type: mongoose.Schema.Types.ObjectId,
        ref: 'User',
        required: true
    }
})

module.exports = mongoose.model('Task', taskScheme);

And here is adminController, im getting the error inside addNewTask

const Task = require("../models/task");

exports.addNewTask = (req, res, next) => {
    const taskDesc = req.body.taskDesc;
    const userId = req.user._id;
    console.log('taskDesc is: ', taskDesc);
    console.log('req.user is: ', req.user) // Output: 'req.user is:  undefined' 
    
    const newTask = new Task(
        {
        description: taskDesc,
        status: 'In Progress',
        userId: userId //get somehow userId , but need first maybe to validate and when moving to all tasks page
        }
    );

    newTask.save()
        .then(() => {
            console.log('Task created');
            res.redirect('/');
        })
        .catch((err) => {
            console.log(err);
        })
}

//TODO: +add: check what user is connected and than deleted the task with the correct userid to match the id in the db
exports.removeTask = (req, res, next) => {
    const taskId = req.body.taskId;

    Task.findByIdAndRemove({
        _id: taskId
    })
        .then(() => {
            res.redirect('/')
        })
        .catch(err => {
            console.log('removeTask error: ', err);
        });
}
//TODO: same things as i wrote in removeTask
exports.editTaskToFinish = (req, res, next) => {
    const taskId = req.body.taskId;
    Task.findByIdAndUpdate(
        {_id: taskId},
        {$set: {status: 'Done'}})
        .then(() => {
            res.redirect('/');
        })
        .catch((err) => {
            console.log('editTaskToFinish: ', err)
            res.redirect('/');
        })
}

brute test:

addNewTask is working when iv replaced the req.user._id with the _id that appears inside the user in mongodb

so i dont really know why it cant see the _id inside the User scheme

If you any further information please let me know