How can I configure a special error page for a certain exception

You can configure error pages in the web.xml located in folder /webapps/ivy/WEB-INF. Add the following configuration:

< error-page >
    < exception-type >java.lang.Throwable< exception-type >
    < location >/myErrorPage.xhtml< location >
< error-page >

Replace java.lang.Throwable with the exception class for which you want to have a special error page.

Another possiblity is to use the normal error page already configured (e.g. ivy-error-page.xhtml) and change it so that it displays different messages for different exception types. In the error page you have access to the errorPage variable that is of type ch.ivyteam.ivy.webserver.ErrorPageMBean. The errorPage variable provides access to the exception object that causes the error handling. With this information you can switch the error page output depending on the exception type.

More information about error page and error handling can be found here.