WordPress 3.5 Breaks Admin Dashboard Items

I recently updated one of my sites to WordPress to version 3.5 on a site that was running a minimal amount of plugins and a simple Woothemes template. While the site still displayed normally, a lot of admin menus and functionality seemed to be broken:

• The Visual Editor didn’t display
• The Add Media button didn’t do anything
• The none of the sidebar menus displayed their child menus on hover
• The “Select All” checkbox on post lists or the Plugins page did nothing

Of course, you always want to some quick steps to see if a plugin or theme is causing the problem:

1. Deactivate your current theme and switch to the new Twenty Twelve theme
2. Deactivate all plugins. If everything works, enable them one-by-one to find the culprit

Unfortunately, the 2 steps above did not solve my problem. It persisted. After more google searches and thanks to this post, I was able to put the line of code listed below in my wp_config.php file and the problem went away. That simple. Add this line of code to your wp_config.php file:

define('CONCATENATE_SCRIPTS', false );

I read other posts that changing define('WP_DEBUG', false); to define('WP_DEBUG', true); worked for others. For me, it did nothing.