node js with gmail api, The API returned an error: Error: unauthorized_client

Question

Edit: The error is happening on on this piece of code:

   var gmail = google.gmail('v1');
      gmail.users.labels.list({
        auth: auth,
        userId: 'me',
      }, function(err, response) {
        if (err) {
          console.log('The API returned an error: ' + err);
          return;
        }

I am using gmail api with Node js. When I go through their quickstart guide I keep getting this error.

https://developers.google.com/gmail/api/quickstart/nodejs

 The API returned an error: Error: unauthorized_client

Keep in mind, I went through the quickstart with my email adress, everything was fine. No errors at all. I decided to create a dummy email for test purposes. The only change I made was step 1-g switching out the client_secret.json files to hold the new credentials and key. I tried switching back to my old file but, the error still persists.

At the bottom of the page in the link provided it states.

Authorization information is stored on the file system, so subsequent executions will not prompt for authorization. Would I have to clear or refresh the information? If so how can I do this?

If it helps I will repost all the code in my quickstart.js file.

var fs = require('fs');
var readline = require('readline');
var google = require('googleapis');
var googleAuth = require('google-auth-library');

var SCOPES = ['https://www.googleapis.com/auth/gmail.readonly'];
var TOKEN_DIR = (process.env.HOME || process.env.HOMEPATH ||
    process.env.USERPROFILE) + '/.credentials/';
var TOKEN_PATH = TOKEN_DIR + 'gmail-nodejs-quickstart.json';

// Load client secrets from a local file.
fs.readFile('client_secret.json', function processClientSecrets(err, content) {
  if (err) {
    console.log('Error loading client secret file: ' + err);
    return;
  }
  // Authorize a client with the loaded credentials, then call the
  // Gmail API.
  authorize(JSON.parse(content), listLabels);
});

/**
 * Create an OAuth2 client with the given credentials, and then execute the
 * given callback function.
 *
 * @param {Object} credentials The authorization client credentials.
 * @param {function} callback The callback to call with the authorized client.
 */
function authorize(credentials, callback) {
  var clientSecret = credentials.installed.client_secret;
  var clientId = credentials.installed.client_id;
  var redirectUrl = credentials.installed.redirect_uris[0];
  var auth = new googleAuth();
  var oauth2Client = new auth.OAuth2(clientId, clientSecret, redirectUrl);

  // Check if we have previously stored a token.
  fs.readFile(TOKEN_PATH, function(err, token) {
    if (err) {
      getNewToken(oauth2Client, callback);
    } else {
      oauth2Client.credentials = JSON.parse(token);
      callback(oauth2Client);
    }
  });
}

/**
 * Get and store new token after prompting for user authorization, and then
 * execute the given callback with the authorized OAuth2 client.
 *
 * @param {google.auth.OAuth2} oauth2Client The OAuth2 client to get token for.
 * @param {getEventsCallback} callback The callback to call with the authorized
 *     client.
 */
function getNewToken(oauth2Client, callback) {
  var authUrl = oauth2Client.generateAuthUrl({
    access_type: 'offline',
    scope: SCOPES
  });
  console.log('Authorize this app by visiting this url: ', authUrl);
  var rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
  });
  rl.question('Enter the code from that page here: ', function(code) {
    rl.close();
    oauth2Client.getToken(code, function(err, token) {
      if (err) {
        console.log('Error while trying to retrieve access token', err);
        return;
      }
      oauth2Client.credentials = token;
      storeToken(token);
      callback(oauth2Client);
    });
  });
}

/**
 * Store token to disk be used in later program executions.
 *
 * @param {Object} token The token to store to disk.
 */
function storeToken(token) {
  try {
    fs.mkdirSync(TOKEN_DIR);
  } catch (err) {
    if (err.code != 'EEXIST') {
      throw err;
    }
  }
  fs.writeFile(TOKEN_PATH, JSON.stringify(token));
  console.log('Token stored to ' + TOKEN_PATH);
}

/**
 * Lists the labels in the user's account.
 *
 * @param {google.auth.OAuth2} auth An authorized OAuth2 client.
 */
function listLabels(auth) {
  var gmail = google.gmail('v1');
  gmail.users.labels.list({
    auth: auth,
    userId: 'me',
  }, function(err, response) {
    if (err) {
      console.log('The API returned an error: ' + err);
      return;
    }
    var labels = response.labels;
    if (labels.length == 0) {
      console.log('No labels found.');
    } else {
      console.log('Labels:');
      for (var i = 0; i < labels.length; i++) {
        var label = labels[i];
        console.log('- %s', label.name);
      }
    }
  });
}

Answer 1

I did a console.log on TOKEN_PATH, it gave me the path of where the file was.

I had to delete the file

/Users/user/.credentials/gmail-nodejs-quickstart.json

which was a hidden folder I could not find on my mac.