Updated from 1.7.2 to 2.1, now every page is 404

[eluser]Unknown[/eluser]
I just updated our install from 1.7.2 to 2.1.0, and now every page I try to pull up is a 404. I'm not even sure where to start. Could it have to with the .htaccess file? Here's what's in there:

Code:

<IfModule mod_rewrite.c>
  RewriteEngine On
  RewriteBase /

#Removes access to the system folder by users.
#Additionally this will allow you to create a System.php controller,
#previously this would not have been possible.
#'system' can be replaced if you have renamed your system folder.
  RewriteCond %{REQUEST_URI} ^system.*
  RewriteRule ^(.*)$ /rootpath/www/index.php/$1 [L]

#Checks to see if the user is attempting to access a valid file,
#such as an image or css document, if this isn't true it sends the
#request to index.php
  RewriteCond %{REQUEST_FILENAME} !-f
#RewriteCond %{REQUEST_FILENAME} !-d
  RewriteRule ^(.*)$ /rootpath/www/index.php/$1 [L]
</IfModule>

<IfModule !mod_rewrite.c>
# If we don't have mod_rewrite installed, all 404's
# can be sent to index.php, and everything works as normal.
# Submitted by: ElliotHaughin

  ErrorDocument 404 /index.php
</IfModule>

Thanks for any help/pointers.

Dave

[eluser]InsiteFX[/eluser]
1) Did you copy the new index.php file over?
2) Did you fix your controllers and models CI_Controller CI_Model
3) Did you fix all your Constructors?

Code:

public function __construct()
{
    parent::__construct();
}