PKIX path building failed, but the certificate is in cacerts
<p>I have the problem that is also described <a href="https://stackoverflow.com/questions/9619030/resolving-javax-net-ssl-sslhandshakeexception-sun-security-validator-validatore?rq=1">here</a>.
The thing is that I created a certificate and added it to the keystore of tomcat, and then I copied it to the <code>cacerts</code> truststore. However, somehow I still get this error.</p>

<p><strong>What I have done:</strong></p>

<blockquote>
  <p>1) keytool -genkey -alias cas -keyalg RSA -keystore cas.keystore
  -storepass changeit</p>
  
  <p>2) keytool -exportcert -alias cas -file cas.crt -keystore cas.keystore</p>
</blockquote>

<p>Step 2) because I wanted to put the certificate in my tomcat keystore and <code>cacerts</code></p>

<blockquote>
  <p>3) keytool -import -alias cas -file cas.crt -keystore "C:\Program
  Files\Java\jdk1.8.0_77\jre\lib\security\cacerts"</p>
  
  <p>4) keytool -import -alias cas -file "C:\Program
  Files\Java\jdk1.8.0_7\jre\bin\cas.crt" -keystore
  "D:\portal\apache-tomcat-8.0.3\conf\portal.keystore"</p>
</blockquote>

<p>So now with step 3 and 4 I added the certificate in my tomcat keystore and the truststore <code>cacerts</code>. </p>

<p>Now I can list my trust- and keystore</p>

<p>With this command..</p>

<blockquote>
  <p>keytool -list -v -keystore "C:\Program
  Files\Java\jdk1.8.0_77\jre\lib\security\cacerts" -alias cas</p>
</blockquote>

<p>... I get this:</p>

<pre><code>Keystore-Kennwort eingeben:
Aliasname: cas
Erstellungsdatum: 09.09.2016
Eintragstyp: trustedCertEntry

Eigentümer: CN=xxx, OU=xxx, O=xxx, L=xxx, ST=xxx, C=xxx
Aussteller: CN=xxx, OU=xxx, O=xxx, L=xxx, ST=xxx, C=xxx
Seriennummer: xxx
Gültig von: Fri Sep 09 10:40:55 CEST 2016 bis: Thu Dec 08 09:40:55 CET 2016
Zertifikat-Fingerprints:
         MD5:  ....
         SHA1: ....
         SHA256: ....
         Signaturalgorithmusname: SHA256withRSA
         Version: 3

Erweiterungen:

#1: ObjectId: 2.5.29.14 Criticality=false
SubjectKeyIdentifier [
KeyIdentifier [...
]
]
</code></pre>

<p>And with this:</p>

<blockquote>
  <p>keytool -list -v -keystore
  "D:\portal\apache-tomcat-8.0.30\conf\portal.keystore" -alias cas</p>
</blockquote>

<p>I get this:</p>

<pre><code>Keystore-Kennwort eingeben:

Keystore-Typ: JKS
Keystore-Provider: SUN

Keystore enthält 1 Eintrag

Aliasname: cas
Erstellungsdatum: 09.09.2016
Eintragstyp: trustedCertEntry

    Eigentümer: CN=xxx, OU=xxx, O=xxx, L=xxx, ST=xxx, C=xxx
    Aussteller: CN=xxx, OU=xxx, O=xxx, L=xxx, ST=xxx, C=xxx
Seriennummer: ...
Gültig von: Fri Sep 09 10:40:55 CEST 2016 bis: Thu Dec 08 09:40:55 CET 2016
Zertifikat-Fingerprints:
         MD5:  ...
         SHA1: ...
         SHA256: ...
         Signaturalgorithmusname: SHA256withRSA
         Version: 3

Erweiterungen:

#1: ObjectId: 2.5.29.14 Criticality=false
SubjectKeyIdentifier [
KeyIdentifier [
]

]
</code></pre>

<p>If it is not clear: the certificates (cas) are the same. </p>

<p>So my impression was that the certificate is now in the keystore of the tomcat server and the truststore <code>cacerts</code>. But somehow I still get this exception when I entered my credentials on the CAS server and get redirected (full stacktrace bellow):</p>

<pre><code>HTTP Status 500 - 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
</code></pre>

<p>These are my connectors in my tomcats <code>server.xml</code>:</p>

<pre><code>&lt;Connector port="8743" protocol="org.apache.coyote.http11.Http11Protocol" SSLEnabled="true"
               maxThreads="150" scheme="https" keystoreFile="${catalina.base}/conf/portal.keystore" keystorePass="changeit" 
               secure="true" connectionTimeout="240000" 
               clientAuth="false" sslProtocol="TLS" allowUnsafeLegacyRenegotiation="true" /&gt;

    &lt;!-- Define an AJP 1.3 Connector on port 8009 --&gt;
    &lt;Connector port="8309" protocol="AJP/1.3" redirectPort="8743" /&gt;
</code></pre>

<p>What is the possible cause of my problem? All the other threads like the one mentioned in the beginning point out that the OP did not import the certificate to the cacerts file, but I did. </p>

<p>The full stacktrace:</p>

<pre><code>09-Sep-2016 12:05:30.146 SEVERE [http-bio-8743-exec-4] org.apache.catalina.core.StandardWrapperValve.invoke Servlet.service() for servlet [default] in context with path [/cas-sample] threw exception
 java.lang.RuntimeException: 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
    at org.jasig.cas.client.util.CommonUtils.getResponseFromServer(CommonUtils.java:443)
    at org.jasig.cas.client.validation.AbstractCasProtocolUrlBasedTicketValidator.retrieveResponseFromServer(AbstractCasProtocolUrlBasedTicketValidator.java:41)
    at org.jasig.cas.client.validation.AbstractUrlBasedTicketValidator.validate(AbstractUrlBasedTicketValidator.java:193)
    at org.jasig.cas.client.validation.AbstractTicketValidationFilter.doFilter(AbstractTicketValidationFilter.java:204)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:521)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1096)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:674)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:279)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)
Caused by: 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
    at sun.security.ssl.Alerts.getSSLException(Alerts.java:192)
    at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1949)
    at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:302)
    at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:296)
    at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1509)
    at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:216)
    at sun.security.ssl.Handshaker.processLoop(Handshaker.java:979)
    at sun.security.ssl.Handshaker.process_record(Handshaker.java:914)
    at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1062)
    at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1375)
    at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1403)
    at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1387)
    at sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:559)
    at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:185)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1513)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1441)
    at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:254)
    at org.jasig.cas.client.util.CommonUtils.getResponseFromServer(CommonUtils.java:429)
    ... 20 more
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:387)
    at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:292)
    at sun.security.validator.Validator.validate(Validator.java:260)
    at sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:324)
    at sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:229)
    at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:124)
    at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1491)
    ... 33 more
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.provider.certpath.SunCertPathBuilder.build(SunCertPathBuilder.java:141)
    at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:126)
    at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:280)
    at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:382)
    ... 39 more
</code></pre>