If you are getting a bit tired and weary of the default 4D Business Kit's "page not found" title page when you first connect your browser to the Business Kit server, don't worry. Just edit the page like you do with all other html pages created by 4D Business Kit.
The "page not found" page is coincidentally called pagenotfound.htm. This page resides on the WebGenericPages subfolder of your 4D Business Kit folder. All other pages in this folder can also be modified.