This article will show you how to update your Custom 404 Message.
Important Note:
Custom 404 messages do not take effect immediately. The page will need to go through an app pool recycle for the page to be updated. This recycling happens automatically every night.
Who can use this feature?
System Administrators | Owners
Instructions
Navigate to the Modules, select the Site Tools tab, and click Custom404:

Edit the Custom 404 Message:

Click Save and Publish:
