java.io.IOException: Hostname was not verified

In addition to @Noam's answer, this is a complete example:

/**
 * Disables the SSL certificate checking for new instances of {@link HttpsURLConnection} This has been created to
 * aid testing on a local box, not for use on production.
 */
private static void disableSSLCertificateChecking() {
    TrustManager[] trustAllCerts = new TrustManager[] {
        new X509TrustManager() {

            @Override
            public void checkClientTrusted(java.security.cert.X509Certificate[] x509Certificates, String s) throws java.security.cert.CertificateException {
                // not implemented
            }

            @Override
            public void checkServerTrusted(java.security.cert.X509Certificate[] x509Certificates, String s) throws java.security.cert.CertificateException {
                // not implemented
            }

            @Override
            public java.security.cert.X509Certificate[] getAcceptedIssuers() {
                return null;
            }

        }
    };

    try {

        HttpsURLConnection.setDefaultHostnameVerifier(new HostnameVerifier() {

            @Override
            public boolean verify(String s, SSLSession sslSession) {
                return true;
            }

        });
        SSLContext sc = SSLContext.getInstance("TLS");
        sc.init(null, trustAllCerts, new java.security.SecureRandom());
        HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());

    } catch (KeyManagementException e) {
        e.printStackTrace();
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
}

Hope it helps

This might happen because the CN (Common Name) you have declared on your SSL does not mach the actual URL you are sending your HTTP request too.

If so, create a new SSL and enter the currect CN. That should fix the problem.

In case you are running with certificates that doesn't mean anything and you want to bypass them you also need to add a null host name verifier to make this code work

HttpsURLConnection.setDefaultHostnameVerifier(new NullHostNameVerifier());
SSLContext context = SSLContext.getInstance("TLS");
context.init(null, new X509TrustManager[]{new NullX509TrustManager()}, new SecureRandom());
HttpsURLConnection.setDefaultSSLSocketFactory(context.getSocketFactory());

And the code for the host:

import javax.net.ssl.HostnameVerifier ;
import javax.net.ssl.SSLSession;

public class NullHostNameVerifier implements HostnameVerifier {

    @Override   
    public boolean verify(String hostname, SSLSession session) {
        Log.i("RestUtilImpl", "Approving certificate for " + hostname);
        return true;
    }

}

This needs to run once, but if you are making changes to your connection object you might need to run it again.