How to solve server connection problem on Android API 20 and below?

Question

Java

The application accesses the php file on the server using OkHttp. On Android API 20 and above, everything works. If the API is below 20, then the following errors occur:

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07-17 16:19:58.612 1509-1524/com.example.verum.optron001 W/System.err: javax.net.ssl.SSLHandshakeException: java.security.cert.CertPathValidatorException: Trust anchor for certification path not found.
07-17 16:19:58.612 1509-1524/com.example.verum.optron001 W/System.err:     at org.apache.harmony.xnet.provider.jsse.OpenSSLSocketImpl.startHandshake(OpenSSLSocketImpl.java:381)
07-17 16:19:58.616 1509-1524/com.example.verum.optron001 W/System.err:     at okhttp3.internal.connection.RealConnection.connectTls(RealConnection.java:302)
07-17 16:19:58.616 1509-1524/com.example.verum.optron001 W/System.err:     at okhttp3.internal.connection.RealConnection.establishProtocol(RealConnection.java:270)
07-17 16:19:58.620 1509-1524/com.example.verum.optron001 W/System.err:     at okhttp3.internal.connection.RealConnection.connect(RealConnection.java:162)
07-17 16:19:58.624 1509-1524/com.example.verum.optron001 W/System.err:     at okhttp3.internal.connection.StreamAllocation.findConnection(StreamAllocation.java:257)
07-17 16:19:58.624 1509-1524/com.example.verum.optron001 W/System.err:     at okhttp3.internal.connection.StreamAllocation.findHealthyConnection(StreamAllocation.java:135)
07-17 16:19:58.624 1509-1524/com.example.verum.optron001 W/System.err:     at okhttp3.internal.connection.StreamAllocation.newStream(StreamAllocation.java:114)
07-17 16:19:58.624 1509-1524/com.example.verum.optron001 W/System.err:     at okhttp3.internal.connection.ConnectInterceptor.intercept(ConnectInterceptor.java:42)
07-17 16:19:58.624 1509-1524/com.example.verum.optron001 W/System.err:     at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:147)
07-17 16:19:58.624 1509-1524/com.example.verum.optron001 W/System.err:     at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:121)
07-17 16:19:58.624 1509-1524/com.example.verum.optron001 W/System.err:     at okhttp3.internal.cache.CacheInterceptor.intercept(CacheInterceptor.java:93)
07-17 16:19:58.624 1509-1524/com.example.verum.optron001 W/System.err:     at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:147)
07-17 16:19:58.624 1509-1524/com.example.verum.optron001 W/System.err:     at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:121)
07-17 16:19:58.624 1509-1524/com.example.verum.optron001 W/System.err:     at okhttp3.internal.http.BridgeInterceptor.intercept(BridgeInterceptor.java:93)
07-17 16:19:58.628 1509-1524/com.example.verum.optron001 W/System.err:     at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:147)
07-17 16:19:58.628 1509-1524/com.example.verum.optron001 W/System.err:     at okhttp3.internal.http.RetryAndFollowUpInterceptor.intercept(RetryAndFollowUpInterceptor.java:126)
07-17 16:19:58.628 1509-1524/com.example.verum.optron001 W/System.err:     at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:147)
07-17 16:19:58.628 1509-1524/com.example.verum.optron001 W/System.err:     at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:121)
07-17 16:19:58.628 1509-1524/com.example.verum.optron001 W/System.err:     at okhttp3.RealCall.getResponseWithInterceptorChain(RealCall.java:200)
07-17 16:19:58.632 1509-1524/com.example.verum.optron001 W/System.err:     at okhttp3.RealCall$AsyncCall.execute(RealCall.java:147)
07-17 16:19:58.632 1509-1524/com.example.verum.optron001 W/System.err:     at okhttp3.internal.NamedRunnable.run(NamedRunnable.java:32)
07-17 16:19:58.632 1509-1524/com.example.verum.optron001 W/System.err:     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
07-17 16:19:58.632 1509-1524/com.example.verum.optron001 W/System.err:     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
07-17 16:19:58.632 1509-1524/com.example.verum.optron001 W/System.err:     at java.lang.Thread.run(Thread.java:856)
07-17 16:19:58.632 1509-1524/com.example.verum.optron001 W/System.err: Caused by: java.security.cert.CertificateException: java.security.cert.CertPathValidatorException: Trust anchor for certification path not found.
07-17 16:19:58.632 1509-1524/com.example.verum.optron001 W/System.err:     at org.apache.harmony.xnet.provider.jsse.TrustManagerImpl.checkTrusted(TrustManagerImpl.java:276)
07-17 16:19:58.636 1509-1524/com.example.verum.optron001 W/System.err:     at org.apache.harmony.xnet.provider.jsse.TrustManagerImpl.checkServerTrusted(TrustManagerImpl.java:197)
07-17 16:19:58.636 1509-1524/com.example.verum.optron001 W/System.err:     at org.apache.harmony.xnet.provider.jsse.OpenSSLSocketImpl.verifyCertificateChain(OpenSSLSocketImpl.java:584)
07-17 16:19:58.636 1509-1524/com.example.verum.optron001 W/System.err:     at org.apache.harmony.xnet.provider.jsse.NativeCrypto.SSL_do_handshake(Native Method)
07-17 16:19:58.636 1509-1524/com.example.verum.optron001 W/System.err:     at org.apache.harmony.xnet.provider.jsse.OpenSSLSocketImpl.startHandshake(OpenSSLSocketImpl.java:378)
07-17 16:19:58.636 1509-1524/com.example.verum.optron001 W/System.err: 	... 23 more
07-17 16:19:58.636 1509-1524/com.example.verum.optron001 W/System.err: Caused by: java.security.cert.CertPathValidatorException: Trust anchor for certification path not found.
07-17 16:19:58.636 1509-1524/com.example.verum.optron001 W/System.err: 	... 28 more

Who can faced similar?
The code that connects to the server:

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public  void signInClick(View view) {

        numberField = findViewById(R.id.numberPhone);
        passwordField = findViewById(R.id.password);

        numberPhone = numberField.getText().toString();
        String password = passwordField.getText().toString();

        /*String hostname = "000webhostapp.com";

        CertificatePinner certificatePinner = new CertificatePinner.Builder()
                .add(hostname, "sha256/c95d249a927d79db828e18296aee11d211fb7d95327971277ff83b13f8d5b466=")
                .build();*/

        OkHttpClient client =  new OkHttpClient();;

        String url = "https://optron001.000webhostapp.com/signIn.php?numberPhone=" + numberPhone + "&password=" + password;
        //создаем запрос к серверу
        Request request = new Request.Builder().url(url).build();

        //выполняем запрос и получаем ответ
        client.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                LoginActivity.this.runOnUiThread(new Runnable() {
                    @Override
                    public void run() {  showMessege("Отсутствует подключение к интеренету"); } });
                e.printStackTrace();
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                if (response.isSuccessful()) {
                    final byte[] check = response.body().bytes();
                    LoginActivity.this.runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            if(check[0] == 49)
                                startMaps();
                            else if(check[0] == 50)
                                showMessege("Несуществующий пользователь");
                            else
                                showMessege("Неверный пароль");
                        }
                    });
                }
                else
                    LoginActivity.this.runOnUiThread(new Runnable() {
                        @Override
                        public void run() {  showMessege("Сервер недоступен"); } });
            }
        });
    }

Answer 1

The log says that the problem is with the ssl certificate. Or you need to edit the certificate on the server, or disable ssl verification on the device.