java.lang.ClassCastException: androidx.appcompat.widget.AppCompatImageButton cannot be cast to android.widget.Button

Problem:
I have a java/xml file in android studio. I need to play two buttons; One for "Map page" and second for "Create new account" (Signup activity). The first button work, but the second close my app. What is the problem?

What I know:
if it is empty xml file the button for to go to the xml file work.

The errors:

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.sampleapp, PID: 8062
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.sampleapp/com.example.sampleapp.SignUpActivity}: java.lang.ClassCastException: androidx.appcompat.widget.AppCompatImageButton cannot be cast to android.widget.Button
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3270)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
     Caused by: java.lang.ClassCastException: androidx.appcompat.widget.AppCompatImageButton cannot be cast to android.widget.Button
        at com.example.sampleapp.SignUpActivity.onCreate(SignUpActivity.java:33)
        at android.app.Activity.performCreate(Activity.java:7802)
        at android.app.Activity.performCreate(Activity.java:7791)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1299)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3245)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016) 
        at android.os.Handler.dispatchMessage(Handler.java:107) 
        at android.os.Looper.loop(Looper.java:214) 
        at android.app.ActivityThread.main(ActivityThread.java:7356) 
        at java.lang.reflect.Method.invoke(Native Method) 

Scripts:

LoginActivity.java:

package com.example.sampleapp;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class LoginActivity extends AppCompatActivity {
    public EditText username;
    public EditText password;
    public TextView errorView;
    public Button login;
    public Button createNewAccount;

    public void initMapPage(){
        Intent mapPage = new Intent(LoginActivity.this, MainActivity.class);
        startActivity(mapPage);
        finish();
    }

    public void initSignUpPage(){
        Intent signUpPage = new Intent(LoginActivity.this, SignUpActivity.class);
        startActivity(signUpPage);
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
        username = (EditText) findViewById(R.id.UsernameBox);
        password = (EditText) findViewById(R.id.PasswordBox);
        errorView = (TextView) findViewById(R.id.errorView);
        login = (Button) findViewById(R.id.LoginButton);
        createNewAccount = (Button) findViewById(R.id.SignupButton);

        login.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String errorMsg = "";
                if (username.getText().toString().equals("") || password.getText().toString().equals("")) {
                    if (username.getText().toString().equals("")) {
                        errorMsg += "Username block is empty\n";
                    }
                    if (password.getText().toString().equals("")) {
                        errorMsg += "Password block is empty\n";
                    }

                    errorView.setText(errorMsg);
                }
                else {
                    initMapPage();
                }
            }
        });

        createNewAccount.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                initSignUpPage();
            }
        });
    }
}

activity_login.xml:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".LoginActivity">

    <TextView
        android:id="@+id/WelcomeBox"
        android:layout_width="210dp"
        android:layout_height="101dp"
        android:layout_marginTop="64dp"
        android:text="Welcome \nTo Our App!"
        android:textAlignment="center"
        android:textColor="#000000"
        android:textSize="30sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/UsernameBox"
        android:layout_width="300dp"
        android:layout_height="55dp"
        android:layout_marginTop="40dp"
        android:ems="10"
        android:hint="Username"
        android:inputType="textPersonName"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/WelcomeBox" />

    <EditText
        android:id="@+id/PasswordBox"
        android:layout_width="300dp"
        android:layout_height="55dp"
        android:layout_marginTop="24dp"
        android:ems="10"
        android:hint="Password"
        android:inputType="textPassword"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/UsernameBox" />

    <Button
        android:id="@+id/SignupButton"
        android:layout_width="237dp"
        android:layout_height="55dp"
        android:layout_marginTop="24dp"
        android:text="Create New Acount"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView4" />

    <Button
        android:id="@+id/LoginButton"
        android:layout_width="115dp"
        android:layout_height="63dp"
        android:layout_marginTop="12dp"
        android:text="LOGIN"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/errorView" />

    <TextView
        android:id="@+id/textView4"
        android:layout_width="60dp"
        android:layout_height="29dp"
        android:layout_marginTop="24dp"
        android:text="OR"
        android:textAlignment="center"
        android:textColor="#D3000000"
        android:textSize="24sp"
        android:textStyle="bold"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/LoginButton" />

    <TextView
        android:id="@+id/errorView"
        android:layout_width="209dp"
        android:layout_height="62dp"
        android:layout_marginTop="16dp"
        app:layout_constraintEnd_toEndOf="parent"
        android:textAlignment="center"
        android:textColor="#FF0000"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/PasswordBox" />

</androidx.constraintlayout.widget.ConstraintLayout>

SignUpActivity.java:

package com.example.sampleapp;

import androidx.appcompat.app.AppCompatActivity;

import android.annotation.SuppressLint;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

public class SignUpActivity extends AppCompatActivity {

    public Button backToLogin;
    public Button SignUp;
    public EditText username;
    public EditText password;
    public EditText email;


    public void initLoginPage(){
        Intent loginPage = new Intent(SignUpActivity.this, LoginActivity.class);
        startActivity(loginPage);
        finish();
    }

    @SuppressLint("WrongViewCast")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_sign_up);
        SignUp = (Button) findViewById(R.id.suButton);
        backToLogin = (Button) findViewById(R.id.back_to_login);
        username = (EditText) findViewById(R.id.UsernameBoxSignUp);
        password = (EditText) findViewById(R.id.PasswordBoxSignUp);
        email = (EditText) findViewById(R.id.EmailBox);

        backToLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                initLoginPage();
            }
        });
    }
}

activity_sign_up.xml:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".SignUpActivity">

    <EditText
        android:id="@+id/UsernameBoxSignUp"
        android:layout_width="300dp"
        android:layout_height="40dp"
        android:layout_marginStart="54dp"
        android:layout_marginTop="160dp"
        android:ems="10"
        android:hint="Username"
        android:inputType="textPersonName"
        android:textSize="18sp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/back_to_login" />

    <EditText
        android:id="@+id/PasswordBoxSignUp"
        android:layout_width="300dp"
        android:layout_height="40dp"
        android:layout_marginStart="55dp"
        android:layout_marginTop="20dp"
        android:ems="10"
        android:hint="Password"
        android:inputType="textPassword"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/EmailBox" />

    <Button
        android:id="@+id/suButton"
        android:layout_width="170dp"
        android:layout_height="53dp"
        android:layout_marginStart="120dp"
        android:layout_marginTop="36dp"
        android:text="SignUp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/PasswordBoxSignUp" />

    <EditText
        android:id="@+id/EmailBox"
        android:layout_width="300dp"
        android:layout_height="40dp"
        android:layout_marginStart="44dp"
        android:layout_marginTop="16dp"
        android:ems="10"
        android:hint="Email"
        android:inputType="textEmailAddress"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/UsernameBoxSignUp" />

    <ImageButton
        android:id="@+id/back_to_login"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="54dp"
        android:layout_marginTop="28dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:srcCompat="?attr/actionModeCloseDrawable" />

</androidx.constraintlayout.widget.ConstraintLayout>

The problem is that ImageButton (and thus also the appcompat version) is a subclass of ImageView, not of Button. You should either change the cast to that, or just remove it entirely if you're only using View methods like setOnClickListener.

Is the username or password text set up?

Android:text="" <!-- If you don't do this, it will be null instead -->
A hint is just a hint, not the actual response. So it gets an error when it looking for something that's not even set up yet.

Your calling SignUpActivity twice

Place the intent

Intent signUpPage = new Intent(LoginActivity.this, SignUpActivity.class);
        startActivity(signUpPage);

on onClick method

and don't forget to add android:onClick="OnCreateAccount" on your button

You are casting button on imagebutton

Just follow this simple step

go to 'SignUpActivity.java' then

public ImageButton backToLogin;
backToLogin = (ImageButton) findViewById(R.id.back_to_login);