Codeigniter by adding ". html" after controller name

Question

I don’t know why when I try to perform an ajax call to the url "http://localhost/meusite/controller/method" I get a 404 error saying the following "The url http://localhost/meusite/controller.html/method" was not found on the server(404). I cannot find where this "comes from. html" it is adding after the controller name, the application is running perfectly on another server.

I don’t know where the problem comes from but I will post . htaccess to see if there is an error in it:

RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php/$1 [L]

And this is the part that makes the requisition:

var controller = 'login';
            var base_url = '<?php echo base_url();?>';

            function validaLogin() {

                $.ajax({
                    'url' : base_url + controller + '/ax_validaLogin',
                    'type' : 'POST', //the way you want to send data to your URL
                    'data' : {'username': document.getElementById('username').value,
                              'senha'  : document.getElementById('senha').value
                             },
                    'success' : function(data){ //probably this request will return anything, it'll be put in var "data"
                        var container = $('#errorMessage'); //jquery selector (get element by id)

                        if(data == "sucesso") {
                            window.location.href='home';
                        }
                        else {
                            if(data){
                                container.html(data);
                                $("#erroLogin").show();
                                focusLogin();
                            }
                        }
                    }
                });
            }   

Remembering that I am using Codeigniter 2, PHP5.6 and Apache2 in a Linux Mint 18.