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.