title: has exceeded the 'max_user_connections' resource
body: <p>I have a MySQL, Express, Angular, NodeJS application and sometimes when I log in I get the following error in my node console:</p>
  
  <blockquote>
    <p>TypeError: Cannot read property 'query' of undefined</p>
  </blockquote>
  
  <p>The error occurs in my <code>passport.local.js</code> file, this is the line:</p>
  
  <pre><code>connection.query('SELECT * FROM users WHERE username LIKE ?', [username], function (err, user) {
  </code></pre>
  
  <p>This is the passport function</p>
  
  <pre><code>passport.use(new LocalStrategy(
      function(username, password, done) {
  
          console.log('app.js');
  
          pool.getConnection(function(err, connection) {
  
              console.log('err: ' + err);
              console.log(connection);    
  
              connection.query('SELECT * FROM users WHERE username LIKE ?', [username], function (err, user) {
                  if (err) throw err;
  
                  for (var i = user.length - 1; i &gt;= 0; i--) {
                      var current = user[i];
                  }
  
                  if(current){
                      if(bcrypt.compareSync(password, current.password)){
                          return done(null, user);
                      } else {
                          return done(null, false);
                      }
                  } else {
                      console.log('no user');
                      return done(null, false);
                  }
              });
  
              connection.release();
          });
      }
  ));
  </code></pre>
  
  <p>I require my <code>pool</code> in the top of my file</p>
  
  <pre><code>var pool = require('../../config/connection');
  </code></pre>
  
  <p>When the error occurs the:</p>
  
  <pre><code>console.log(connection);  
  </code></pre>
  
  <p>Gets:</p>
  
  <blockquote>
    <p>undefined</p>
  </blockquote>
  
  <p>I also log the error:</p>
  
  <pre><code>console.log('err: ' + err);
  </code></pre>
  
  <p>Shows: </p>
  
  <pre><code> err: Error: ER_USER_LIMIT_REACHED: User 'bfe4a8980ede74' has exceeded the 'max_user_connections' resource (current value: 10)
  </code></pre>