Jamming project: Error 404 when trying fetch POST request for saving playlist

Hello everybody,

I am working on Jamming project from Full-stack developer career path and I am stuck at 95 step.
When I try creating the new playlist and add tracks in that playlist, I get this error:

I was searching all over the internet to find a solution, but without any luck :frowning:

This is my code, like it is also in the video tutorial:

Spotify.js

const clientId = 'XXXXXX';
const redirectUri = 'http://localhost:3000/';
let accessToken;

const Spotify = {
   getAccessToken() {
       if (accessToken) {
           return accessToken;
       }

       //check for access token match
       const accessTokenMatch = window.location.href.match(/access_token=([^&]*)/);
       const expiresInMatch = window.location.href.match(/expires_in=([^&]*)/);

       if(accessTokenMatch && expiresInMatch) {
           accessToken = accessTokenMatch[1];
           const expiresIn = Number(expiresInMatch[1]);

           window.setTimeout(() => accessToken = '', expiresIn * 1000);
           window.history.pushState('Acces Token', null, '/');
           return accessToken;

       }
       else {
             const accessUrl = `https://accounts.spotify.com/authorize?client_id=${clientId}&response_type=token&scope=playlist-modify-public&redirect_uri=${redirectUri}`
             window.location = accessUrl;
       }
   },

   search(term) {
       let accessToken = Spotify.getAccessToken();
       return fetch(`https://api.spotify.com/v1/search?type=track&q=${term}`, { headers: 
                                                                                         { Authorization: `Bearer ${accessToken}`}
   }).then(response => {
           return response.json();
   }).then(jsonResponse => {
       if(!jsonResponse.tracks){
           return [];
       }
           return jsonResponse.tracks.items.map(track => ({
               id: track.id,
               name: track.name,
               artist: track.artists[0].name,
               album: track.album.name,
               uri: track.uri
           }));    
               
       
       });
   },

   savePlayList(name, trackUris) {
       if (!name || !trackUris.length) {
           return;
       }

       const accessToken = Spotify.getAccessToken();
       const headers = { Authorization : `Bearer ${accessToken}` };
       let userId;

       return fetch('https://api.spotify.com/v1/me', { headers: headers}
       ).then(response => {  return response.json()}
       ).then(jsonResponse => {
           userId = jsonResponse.id;
           return fetch(`https://api.spotify.com/v1/me/users/${userId}/playlists`, 
           {
                headers: headers,
                method: 'POST',
                'Content-Type': 'application/json',
                body: JSON.stringify( {name : name})
           }).then(response => { 
               console.log(response);
               return response.json() ;
                                } 
           ).then (jsonResponse => {
           const playlistId = jsonResponse.id;
           return fetch(`https://api.spotify.com/v1/playlists/${playlistId}/tracks`, 
           {
               headers: headers,
               method: 'POST',
               'Content-Type': 'application/json',
               body: JSON.stringify( {uris: trackUris})
           });
       });
   });
 }
} 
export default Spotify;

And here is App.js savePlaylist function:

 savePlaylist() {
    const trackURIs = this.state.playlistTracks.map(track => track.uri);
    Spotify.savePlayList(this.state.playlistName, trackURIs).then(() => {
      this.setState( {
        playlistName: 'New Playlist',
        playlistTracks: []
      })
    }).catch((rej) => {console.log(rej); })
  } 

I assume is something wrong on Spotify.js, with fetch POST, but I couldn’t see any misspelling.
Could you please have a look and help me?

Thank you all!