Enable stack trace in Jetty logs

I'm running Artifactory, which is using Jetty a web server.

Sometimes the server is throwing a http 500 error. However there's no accurate message with it.

How do I tell Jetty to enable something like a stack trace or an error messa开发者_如何学Cge related to this error 500, which I can use to troubleshoot this issue?

This is what I currently have:

15309:10.2.50.76 -  -  [29/Aug/2011:19:30:20 +0000] "GET /artifactory/libs-snapshots-local/com/mycompany/project/project-component/8.0.0-SNAPSHOT/maven-metadata.xml HTTP/1.1" 500 7087

I need a proper message saying where the error comes from. Thanks.