Codeigniter无法更改视图页面

I need your help with an issue that is dragging me crazy.

You have to know that My view page has 4 view pages called: Header, Menu, Sub menu and Content and I'm using SQL database to store the information the user fill in Content.

I want to change Content page after the user hit submit button.

The submit button will call a JS that arranges the information into an array and call a controller function that call a database function and fill the table and send a TRUE if the table was filled. After all that code, I take the created array and TRUE and send it to a new Content view and display the information that the user filled and tell him "upload success".

The main problem is the new content view isn't showing, I checked the database and the information is uploaded. This is part of the controller function that is sended to the database.

This is the Javascript, i'm using ajax.

 $("#btn_enviar").click(function(){
    var r = confirm("Los datos ingresados no podran ser modificados una vez enviados, presione aceptar si desea continuar");
    if (r == true){
        var url = base_url + "/inventario/insert_inventario"; 
            $.ajax({ 
               type: "POST",
               url: url,
               data: $("#form_inventario").serialize(), 
               success: function(data)
               {
                   $("#contenido").html(data.mensaje); 
               }
             });
        var elem = document.getElementById('btn_enviar');
    } 
        return false;
});

This is the Controller. array_db is the array with the user information.

$obj_inv = $this->Inventario_model->insert_inventario($array_db);
if($obj_inv){           
        $edit_view = $this->load->view(base_url()."inventario/edit",$array_db,TRUE);
        $response = array('mensaje' => $edit_view
                      );
        $this->output
            ->set_status_header(200)
            ->set_content_type('application/json', 'utf-8')
            ->set_output(json_encode($response, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES))
            ->_display();
    exit;
    } else {
        echo('ERROR: Uno o mas datos son incorrectos o no estan llenados.');        
    }   

This is the model. Inventario_model is the function that calls the database and return a True or False is the information is inserted.

public function insert_inventario($array_data) {

        $id = $this->db->insert('inventario',$array_data);

        $obj_activo  = $this->db->get('inventario');

        return $id;

    }

What I'm missing? Why the edit view isn't showing?

The only clue I have is, in development Console is throwing me this:

http://[IP]/Inventario_Remedy/inventario/insert_inventario Failed to load resource: the server responded with a status of 500 (Internal Server Error)

Edited to show the error log

PHP 1. {main}() C:\Xampp\htdocs\Inventario_Remedy\index.php:0

PHP 2. require_once() C:\Xampp\htdocs\Inventario_Remedy\index.php:293

PHP 3. call_user_func_array() C:\Xampp\htdocs\Inventario_Remedy\system\core\CodeIgniter.php:514

PHP 4. Inventario->insert_inventario() C:\Xampp\htdocs\Inventario_Remedy\system\core\CodeIgniter.php:514

PHP 5. Inventario_model->insert_inventario() C:\Xampp\htdocs\Inventario_Remedy\application\controllers\Inventario.php:105

PHP 6. CI_DB_query_builder->insert() C:\Xampp\htdocs\Inventario_Remedy\application\models\Inventario_model.php:29

PHP 7. CI_DB_driver->query() C:\Xampp\htdocs\Inventario_Remedy\system\database\DB_query_builder.php:1608

PHP 8. CI_DB_driver->display_error() C:\Xampp\htdocs\Inventario_Remedy\system\database\DB_driver.php:675

PHP 9. CI_Exceptions->show_error() C:\Xampp\htdocs\Inventario_Remedy\system\database\DB_driver.php:1698

PHP 10. _error_handler() C:\Xampp\htdocs\Inventario_Remedy\system\database\DB_driver.php:182

PHP 11. CI_Exceptions->show_php_error() C:\Xampp\htdocs\Inventario_Remedy\system\core\Common.php:623

CI VERSION 3.0