Android: Error while installing APKs

Lucie P. :

I'm slowly trying to do some simple tasks in Android Studio. The following app is installed on emulator without any errors. But when I tried to install it on a real device Redmi 3S this error occured:

Unknown failure (Failure - not installed for 0)
Error while Installing APKs

I went through similar questions around here but in these cases the error was caused by not enabled debugging, or not accepitng the app instalation. However, I allowed debugging and I also tried to install some other app in Studio and it worked fine.

So the question probably is, what's wrong with the code.

MainActivity.java

package tlacitko.button;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void sendMessage(View view) {
        new Thread(new Runnable() {
            public void run() {

                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        try{
                            URL url = new URL("http://147.32.186.51:8080");
                           // HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
                            InputStream is = url.openStream();
                            BufferedReader br = new BufferedReader(new
                                    InputStreamReader(is));
                            String s = "";
                        }catch(MalformedURLException ex){

                        }catch(IOException e){
                        }
                    }
                });
            }
        }).start();
    }
}

And the xml code:

activity_main.xml

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Try to connect the server."
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="16dp"
        android:layout_marginRight="7dp"
        android:layout_marginTop="16dp"
        android:onClick="sendMessage"
        android:text="Conncect"
        app:layout_constraintLeft_toRightOf="@+id/editText"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />


</android.support.constraint.ConstraintLayout>

JPZ :

Follow these steps to overcome the issue.

Disconnect all devices connected to system, and close all emulators running on System.
Turn off Instant Run feature from settings.
Perform a clean build.
Turn on Instant Run feature from settings.
Perform a clean build.
Connect your device/start your emulator and ensure it is online.
Run the project by selecting the device/emulator.

Note:

1) You should not have different instances of Android Debug Bridge(adb) running on system.

2) If using Genymotion then make sure that you use the custom sdk path mentioned in the Genymotion settings the which you mentioned in the settings of Android Studio.

These steps are likely to solve your issue, however it may also be a problem with android versions.