How to Solve Notice: Undefined index: highlighted in include() in drupal 7?

To solve this error/notice need to follow below steps.

1. If you have created any block or region need to check the block/region name in .info file of the theme. For example i have created on block/region like..


<?php if ($page['sidebar_third']): ?>
    <aside id="sidebar-third" role="complementary" class="sidebar clearfix">
      <?php print render($page['sidebar_third']); ?>
    </aside>  <!-- /#sidebar-third -->
  <?php endif; ?>
2. Need to add "sidebar_third" in .info file as.
  regions[sidebar_third]  = Third Sidebar
3. Then finally dont forget to disable and enable the theme for which we have done the above functionality.