Log file
Enable single sign-on debug logging with an entry in the following file: <tomcat-home>/webapps/jasperserver-pro/WEB-INF/log4j.properties. For example you might have the following entry: log4j.logger.com.idiominc.ws.integration.reporting.jaspersoft.WSSingleSignOnFilter=debug.
Output for the server will appear in the file: <tomcat-home>/webapps/jasperserver-pro/WEB-INF/logs/jasperserver.log and the Tomcat console window.