Apache Http Client SSL certificate error

In Http Client 4.5.2:

SSLContext sslContext = SSLContexts.custom().loadTrustMaterial(null, 
    new TrustStrategy() {
        @Override
        public boolean isTrusted(final X509Certificate[] chain, final String authType) 
        throws CertificateException {
            return true;
        }
    }).build();

SSLConnectionSocketFactory sslsf;
sslsf = new SSLConnectionSocketFactory(sslContext, NoopHostnameVerifier.INSTANCE);

And then:

HttpClientBuilder builder = HttpClients.custom().setSSLSocketFactory(sslsf);

Please also note that trusting self-signed certs does not mean trusting any arbitrary cert.

Try setting up your SSL context this way:

SSLContext sslContext = SSLContexts.custom().loadTrustMaterial(null, 
    new TrustStrategy() {
        @Override
        public boolean isTrusted(final X509Certificate[] chain, final String authType) 
        throws CertificateException {
            return true;
        }
    })
    .useTLS()
    .build();

Please also note that generally trusting certificates indiscriminately defeats the purpose of using SSL in the first place. Use when absolutely necessary or for testing only