TypeError: Cannot read property 'value' of undefined React

App.js

import React, { Component } from 'react';
import logo from './logo.svg';
import './App.css';

import UserInput from './learn/UserInput';


class App extends Component {


  state = {
    users : [
      {id:1, name:'manu', Age:28},
      {id:2,name:'john', Age:29},
      {id:3,name:'clint', Age:30},
    ]
  }


changeMethod = (event, id) => {

  const userIndex = this.state.users.findIndex( 
      (el) => {
      return  el.id === id;
      }

    ) 

  const user = {
    ...this.state.users[userIndex]
  };

  user.name = event.target.value;

  const users = [...this.state.users];

  users[userIndex] = user;

  this.setState({
    users : users
  })
}




  render() {

      let persons = (
           <div>

            {this.state.users.map( (el, index) => { 

              return (
                <div key ={el.id}>
                <p>{el.name}</p>

                <input type="text" name="" id="" onChange={this.changeMethod.bind(this, el.id)} 
                  value ={el.name}
                  />

                  </div>
              )
              })}

          </div> 
      )


    return (

        <div className="App">
            {persons}
        </div>

    );
  }
}

export default App;

this is the error im getting when i try to enter in the input box

TypeError: Cannot read property 'value' of undefined
App._this.changeMethod
src/App.js:33
  30 |   ...this.state.users[userIndex]
  31 | };
  32 | 
> 33 | user.name = event.target.value;
  34 | 
  35 | const users = [...this.state.users];