Since we can't add annotations to all the exception classes we are interested in, Seam also lets us specify this functionality in pages.xml.

<pages>
   
   <exception class="javax.persistence.EntityNotFoundException">
      <http-error error-code="404"/>
   </exception>
   
   <exception class="javax.persistence.PersistenceException">
      <end-conversation/>
      <redirect view-id="/error.xhtml">
          <message>Database access failed</message>
      </redirect>
   </exception>
   
   <exception>
      <end-conversation/>
      <redirect view-id="/error.xhtml">
          <message>Unexpected failure</message>
      </redirect>
   </exception>
   
</pages>

The last <exception> declaration does not specify a class, and is a catch-all for any exception for which handling is not otherwise specified via annotations or in pages.xml.

You can also access the handled exception instance through EL, Seam places it in the conversation context, e.g. to access the message of the exception:

...
throw new AuthorizationException("You are not allowed to do this!");

<pages>

    <exception class="org.jboss.seam.security.AuthorizationException">
        <end-conversation/>
        <redirect view-id="/error.xhtml">
            <message severity="WARN">#{handledException.message}</message>
        </redirect>
    </exception>

</pages>