Content region not visible in blocks setup page in Sky Adaptive Theme I checked the 'content' region, being one of the prerequisite regions and it is present and referenced in the sky.info file as well as in the page.tpl.php.

That is:
(in sky.info file)

regions[content] = Main content


(in page.tpl.php file)

        &lt;div id="content"&gt;&lt;?php print render($page['content']); ?&gt;&lt;/div&gt; 


However, when I go into the 'block' setup GUI page, from the regions dropdown, I can not see the 'content' region option. 

Any idea as to why its not visible would be great. Cheers
Which version of Sky theme are you using? In 7.x-2.3, I can see the "Main content" region in the drop down list. If you have made custom changes to theme, try clearing the cache.