404 Page

• 404 Page is the page displayed when an HTTP request does not correspond to a resource on the Web server i.e., when a URL is not found and Web Server returns a 404 error code.
• Page is located here - /sitecore/content/EH/Emory/Home/PageNotFound. 
• This page is completely editable in EE.
• Currently, the page has the following components :
  • Hero Banner - Base Hero variant of EH Hero; local datasource item name - Hero Banner.
  • EH Breadcrumb for breadcrumb.
  • Content Spot - for the page content.
• The Header and Footer has been added via Page Design.
• The 404 page is configured in the Settings item (/sitecore/content/EH/Emory/Settings) - Page not found link field.
• Page URL - 404 Page Not Found .

• Header
• Content Spot
• Footer 

Please check out the above manages to manage the 404 page. 

400 Page:

• See Dev Notes