bad Reference to span (prob: navigation bar)

by beukelaer

HTML

<link rel="stylesheet" href="https://getbootstrap.com/docs/4.1/examples/offcanvas/offcanvas.css">
<link rel="stylesheet" href="https://getbootstrap.com/docs/4.1/dist/css/bootstrap.min.css">
<!DOCTYPE html>
<html lang="en"><head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
    <meta name="description" content="">
    <meta name="author" content="">
    <link rel="icon" href="https://getbootstrap.com/favicon.ico">

    <title>Offcanvas template for Bootstrap</title>

    <!-- Bootstrap core CSS -->
    <link href="Offcanvas%20template%20for%20Bootstrap-Dateien/bootstrap.css" rel="stylesheet">

    <!-- Custom styles for this template -->
    <link href="Offcanvas%20template%20for%20Bootstrap-Dateien/offcanvas.css" rel="stylesheet">
  </head>

  <body class="bg-light">

    <nav class="navbar navbar-expand-lg fixed-top navbar-dark bg-dark">
      <a class="navbar-brand mr-auto mr-lg-0" href="#">Offcanvas navbar</a>
      <button class="navbar-toggler p-0 border-0" type="button" data-toggle="offcanvas">
        <span class="navbar-toggler-icon"></span>
      </button>

      <div class="navbar-collapse offcanvas-collapse" id="navbarsExampleDefault">
        <ul class="navbar-nav mr-auto">
          <li class="nav-item active">
            <a class="nav-link" href="#">Dashboard <span class="sr-only">(current)</span></a>
          </li>
          <li class="nav-item">
            <a class="nav-link" href="#">Notifications</a>
          </li>
          <li class="nav-item">
            <a class="nav-link" href="#">Profile</a>
          </li>
          <li class="nav-item">
            <a class="nav-link" href="#">Switch account</a>
          </li>
          <li class="nav-item dropdown">
            <a class="nav-link dropdown-toggle" href="https://example.com/" id="dropdown01" data-toggle="dropdown" aria-haspopup="true"...