When using IBM Web Content Management (WCM), there is no way to change the error pages if 404 errors are returned. For example, when using servlet rendering to render a website, if you try to request a URL that doesn't exist, you are presented with a 404 error.
Is it possible to display a customer page with this error?
Resolving the problem
You can bypass Portal's default behavior by implementing a solution using servlet filters to return custom error pages.
One example of how to implement this solution is covered in detail on the Portal Family Wiki as Custom Error Pages.