<footer id="footer" role="contentinfo">
  <div class="container">
    <p class="pull-right">
      <a class="backToTop" data-scroll href="#">Back to top</a>
    </p>
    <nav>
      <ul class="nav" role="navigation">
        <li class="nav-item">
          <span class="nav-link disabled">© <span itemprop="copyrightYear">{{ now|date('Y') }}</span> {{ siteTitle }}</span>
        </li>
        {% for footerLink in footerLinks %}
          <li class="nav-item">
            <a class="nav-link" href="{{ footerLink.url }}" title="{{ footerLink.title }}"{% if footerLink.rel %} rel="{{ footerLink.rel }}"{% endif %}>
              {{ footerLink.navigation_title }}
            </a>
          </li>
        {% endfor %}
        <li class="nav-item">
          <a class="nav-link" href="http://www.sumocoders.be/?utm_source={{ siteTitle|urlencode }}&amp;utm_medium=credits&amp;utm_campaign=client_sites" rel="external" target="_blank">
            SumoCoders
          </a>
        </li>
      </ul>
    </nav>
  </div>
</footer>

<footer id="footer" role="contentinfo">
  <div class="container">
    <p class="pull-right">
      <a class="backToTop" data-scroll href="#">Back to top</a>
    </p>
    <nav>
      <ul class="nav">
        <li class="nav-item">
          <span class="nav-link disabled">© <span itemprop="copyrightYear">{{ now|date('Y') }}</span> {{ siteTitle }}</span>
        </li>
        {% for footerLink in footerLinks %}
          <li class="nav-item">
            <a class="nav-link" href="{{ footerLink.url }}" title="{{ footerLink.title }}"{% if footerLink.rel %} rel="{{ footerLink.rel }}"{% endif %}>
              {{ footerLink.navigation_title }}
            </a>
          </li>
        {% endfor %}
        <li class="nav-item">
          <a class="nav-link" href="http://www.sumocoders.be/?utm_source={{ siteTitle|urlencode }}&amp;utm_medium=credits&amp;utm_campaign=client_sites" rel="external" target="_blank">
            SumoCoders
          </a>
        </li>
      </ul>
    </nav>
  </div>
</footer>

Remove wrong role navigation on ul
Remove wrong role navigation on ul