Apache HttpClient exception PKIX path building failed

Question

I'm creating an app that automatically login in a web site and execute some tasks, I don't know why when I try to execute a get in a https page I get this exception

Exception in thread "main" 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(Unknown Source)
    at sun.security.ssl.SSLSocketImpl.fatal(Unknown Source)
    at sun.security.ssl.Handshaker.fatalSE(Unknown Source)
    at sun.security.ssl.Handshaker.fatalSE(Unknown Source)
    at sun.security.ssl.ClientHandshaker.serverCertificate(Unknown Source)
    at sun.security.ssl.ClientHandshaker.processMessage(Unknown Source)
    at sun.security.ssl.Handshaker.processLoop(Unknown Source)
    at sun.security.ssl.Handshaker.process_record(Unknown Source)
    at sun.security.ssl.SSLSocketImpl.readRecord(Unknown Source)
    at sun.security.ssl.SSLSocketImpl.performInitialHandshake(Unknown Source)
    at sun.security.ssl.SSLSocketImpl.startHandshake(Unknown Source)
    at sun.security.ssl.SSLSocketImpl.startHandshake(Unknown Source)
    at org.apache.http.conn.ssl.SSLConnectionSocketFactory.connectSocket(SSLConnectionSocketFactory.java:261)
    at org.apache.http.impl.conn.HttpClientConnectionOperator.connect(HttpClientConnectionOperator.java:118)
    at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.connect(PoolingHttpClientConnectionManager.java:314)
    at org.apache.http.impl.execchain.MainClientExec.establishRoute(MainClientExec.java:357)
    at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:218)
    at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:194)
    at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:85)
    at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:108)
    at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:186)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:72)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:214)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:160)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:136)
    at com.paclabs.appmaker.componentes.web.AdsKeyCreator.createAppStartApp(AdsKeyCreator.java:154)
    at com.paclabs.appmaker.core.Main.main(Main.java:80)
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(Unknown Source)
    at sun.security.validator.PKIXValidator.engineValidate(Unknown Source)
    at sun.security.validator.Validator.validate(Unknown Source)
    at sun.security.ssl.X509TrustManagerImpl.validate(Unknown Source)
    at sun.security.ssl.X509TrustManagerImpl.checkTrusted(Unknown Source)
    at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(Unknown Source)
    ... 23 more
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(Unknown Source)
    at java.security.cert.CertPathBuilder.build(Unknown Source)
    ... 29 more

here's the code that is generating this exception:

HtmlResponseHandler handler = new HtmlResponseHandler(httpClient);
HttpGet indexLogin = new   HttpGet
                     ("https://developers.startapp.com/General/Login.aspx");
String retorno = httpClient.execute(indexLogin,handler);
Document doc = Jsoup.parse(retorno);

I only want to make a simple get request with HttpClient, what should I do?

Solution

The simplest (and unsecure) way of solving your problem is to ignore the SSL certificate error passing false to validateTLSCertificates method:

Jsoup
    .connect("https://developers.startapp.com/General/Login.aspx")
    .validateTLSCertificates(false)
    .execute();