I following the demo to set up CAS in my Windows XP machine. Every setup up to Step 9 is running OK

When I run

http://compA:8080/servlets-examples/servlet/HelloWorldExample

It redirects me to open CAS login website

 https://compA:8443/cas/login?service=http%3A%2F%2compA%3A8080%2Fservlets-examples%2Fservlet%2FHelloWorldExample

I input uday/uday and
I come up with following error, How to fix?

HTTP Status 500 -

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception javax.servlet.ServletException: Unable to validate ProxyTicketValidator [[edu.yale.its.tp.cas.client.ProxyTicketValidator proxyList=[null] [edu.yale.its.tp.cas.client.ServiceTicketValidator casValidateUrl=https://edwardscwin.wri.wolfram.com:8443/cas/serviceValidate ticket=[ST-2-dbxeUR3kedj7R0YxBfKbwusLz7YcgmoEbPU-20] service=[http%3A%2F%2Fedwardscwin.wri.wolfram.com%3A8080%2Fservlets-examples%2Fservlet%2FHelloWorldExample] renew=false]]]
edu.yale.its.tp.cas.client.filter.CASFilter.doFilter(CASFilter.java:381)
root cause edu.yale.its.tp.cas.client.CASAuthenticationException: Unable to validate ProxyTicketValidator [[edu.yale.its.tp.cas.client.ProxyTicketValidator proxyList=[null] [edu.yale.its.tp.cas.client.ServiceTicketValidator casValidateUrl=https://edwardscwin.wri.wolfram.com:8443/cas/serviceValidate ticket=[ST-2-dbxeUR3kedj7R0YxBfKbwusLz7YcgmoEbPU-20] service=[http%3A%2F%2Fedwardscwin.wri.wolfram.com%3A8080%2Fservlets-examples%2Fservlet%2FHelloWorldExample] renew=false]]]
edu.yale.its.tp.cas.client.CASReceipt.getReceipt(CASReceipt.java:52)
edu.yale.its.tp.cas.client.filter.CASFilter.getAuthenticatedUser(CASFilter.java:455)
edu.yale.its.tp.cas.client.filter.CASFilter.doFilter(CASFilter.java:378)
root cause javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
com.sun.net.ssl.internal.ssl.Alerts.getSSLException(Unknown Source)
com.sun.net.ssl.internal.ssl.SSLSocketImpl.fatal(Unknown Source)
com.sun.net.ssl.internal.ssl.Handshaker.fatalSE(Unknown Source)
com.sun.net.ssl.internal.ssl.Handshaker.fatalSE(Unknown Source)
com.sun.net.ssl.internal.ssl.ClientHandshaker.serverCertificate(Unknown Source)
com.sun.net.ssl.internal.ssl.ClientHandshaker.processMessage(Unknown Source)
com.sun.net.ssl.internal.ssl.Handshaker.processLoop(Unknown Source)
com.sun.net.ssl.internal.ssl.Handshaker.process_record(Unknown Source)
com.sun.net.ssl.internal.ssl.SSLSocketImpl.readRecord(Unknown Source)
com.sun.net.ssl.internal.ssl.SSLSocketImpl.performInitialHandshake(Unknown Source)
com.sun.net.ssl.internal.ssl.SSLSocketImpl.startHandshake(Unknown Source)
com.sun.net.ssl.internal.ssl.SSLSocketImpl.startHandshake(Unknown Source)
sun.net.www.protocol.https.HttpsClient.afterConnect(Unknown Source)
sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(Unknown Source)
sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(Unknown Source)
edu.yale.its.tp.cas.util.SecureURL.retrieve(SecureURL.java:84)
edu.yale.its.tp.cas.client.ServiceTicketValidator.validate(ServiceTicketValidator.java:212)
edu.yale.its.tp.cas.client.CASReceipt.getReceipt(CASReceipt.java:50)
edu.yale.its.tp.cas.client.filter.CASFilter.getAuthenticatedUser(CASFilter.java:455)
edu.yale.its.tp.cas.client.filter.CASFilter.doFilter(CASFilter.java:378)
root cause sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
sun.security.validator.PKIXValidator.doBuild(Unknown Source)
sun.security.validator.PKIXValidator.engineValidate(Unknown Source)
sun.security.validator.Validator.validate(Unknown Source)
com.sun.net.ssl.internal.ssl.X509TrustManagerImpl.validate(Unknown Source)
com.sun.net.ssl.internal.ssl.X509TrustManagerImpl.checkServerTrusted(Unknown Source)
com.sun.net.ssl.internal.ssl.X509TrustManagerImpl.checkServerTrusted(Unknown Source)
com.sun.net.ssl.internal.ssl.ClientHandshaker.serverCertificate(Unknown Source)
com.sun.net.ssl.internal.ssl.ClientHandshaker.processMessage(Unknown Source)
com.sun.net.ssl.internal.ssl.Handshaker.processLoop(Unknown Source)
com.sun.net.ssl.internal.ssl.Handshaker.process_record(Unknown Source)
com.sun.net.ssl.internal.ssl.SSLSocketImpl.readRecord(Unknown Source)
com.sun.net.ssl.internal.ssl.SSLSocketImpl.performInitialHandshake(Unknown Source)
com.sun.net.ssl.internal.ssl.SSLSocketImpl.startHandshake(Unknown Source)
com.sun.net.ssl.internal.ssl.SSLSocketImpl.startHandshake(Unknown Source)
sun.net.www.protocol.https.HttpsClient.afterConnect(Unknown Source)
sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(Unknown Source)
sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(Unknown Source)
edu.yale.its.tp.cas.util.SecureURL.retrieve(SecureURL.java:84)
edu.yale.its.tp.cas.client.ServiceTicketValidator.validate(ServiceTicketValidator.java:212)
edu.yale.its.tp.cas.client.CASReceipt.getReceipt(CASReceipt.java:50)
edu.yale.its.tp.cas.client.filter.CASFilter.getAuthenticatedUser(CASFilter.java:455)
edu.yale.its.tp.cas.client.filter.CASFilter.doFilter(CASFilter.java:378)
root cause sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
sun.security.provider.certpath.SunCertPathBuilder.engineBuild(Unknown Source)
java.security.cert.CertPathBuilder.build(Unknown Source)
sun.security.validator.PKIXValidator.doBuild(Unknown Source)
sun.security.validator.PKIXValidator.engineValidate(Unknown Source)
sun.security.validator.Validator.validate(Unknown Source)
com.sun.net.ssl.internal.ssl.X509TrustManagerImpl.validate(Unknown Source)
com.sun.net.ssl.internal.ssl.X509TrustManagerImpl.checkServerTrusted(Unknown Source)
com.sun.net.ssl.internal.ssl.X509TrustManagerImpl.checkServerTrusted(Unknown Source)
com.sun.net.ssl.internal.ssl.ClientHandshaker.serverCertificate(Unknown Source)
com.sun.net.ssl.internal.ssl.ClientHandshaker.processMessage(Unknown Source)
com.sun.net.ssl.internal.ssl.Handshaker.processLoop(Unknown Source)
com.sun.net.ssl.internal.ssl.Handshaker.process_record(Unknown Source)
com.sun.net.ssl.internal.ssl.SSLSocketImpl.readRecord(Unknown Source)
com.sun.net.ssl.internal.ssl.SSLSocketImpl.performInitialHandshake(Unknown Source)
com.sun.net.ssl.internal.ssl.SSLSocketImpl.startHandshake(Unknown Source)
com.sun.net.ssl.internal.ssl.SSLSocketImpl.startHandshake(Unknown Source)
sun.net.www.protocol.https.HttpsClient.afterConnect(Unknown Source)
sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(Unknown Source)
sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(Unknown Source)
edu.yale.its.tp.cas.util.SecureURL.retrieve(SecureURL.java:84)
edu.yale.its.tp.cas.client.ServiceTicketValidator.validate(ServiceTicketValidator.java:212)
edu.yale.its.tp.cas.client.CASReceipt.getReceipt(CASReceipt.java:50)
edu.yale.its.tp.cas.client.filter.CASFilter.getAuthenticatedUser(CASFilter.java:455)
edu.yale.its.tp.cas.client.filter.CASFilter.doFilter(CASFilter.java:378)
note The full stack trace of the root cause is available in the Apache Tomcat/5.5.25 logs.

Apache Tomcat/5.5.25