title: After changing developing OS, it shows "Unresolved reference: synthetic"
body: <h1>Abstract</h1>
  <p>I am developing an Android app and I am new to it. I used to develope this app on <strong>Windows 10 Pro</strong> and everything works fine, no error. Recently, I have erased my Windows 10 and use Manjaro Linux (KDE version). When I pull my code from GitHub and open in Android Studio, the line: <code>import kotlinx.android.synthetic.main.activity_login.*</code> shows have the error: <code>Unresolved reference: synthetic</code></p>
  <h1>my imports</h1>
  <pre><code>package com.marco.booking_app.auth
  
  import android.content.Intent
  import android.os.Bundle
  import android.util.Log
  import android.widget.Button
  import android.widget.TextView
  import androidx.appcompat.app.AppCompatActivity
  import com.marco.booking_app.MainActivity
  import com.marco.booking_app.R
  import com.marco.booking_app.extensions.Extensions.toastError
  import com.marco.booking_app.utils.FirebaseUtils.firebaseAuth
  import kotlinx.android.synthetic.main.activity_login.* // It shows &quot;Unresolved reference: synthetic&quot;
  </code></pre>
  <h1>build.gradle (Project)</h1>
  <pre><code>// Top-level build file where you can add configuration options common to all sub-projects/modules.
  buildscript {
      ext.kotlin_version = &quot;1.5.10&quot;
      repositories {
          google()
          mavenCentral()
      }
      dependencies {
          classpath &quot;com.android.tools.build:gradle:4.2.1&quot;
          classpath &quot;org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version&quot;
          classpath 'com.google.gms:google-services:4.3.8'
  
          // NOTE: Do not place your application dependencies here; they belong
          // in the individual module build.gradle files
      }
  }
  
  allprojects {
      repositories {
          google()
          mavenCentral()
          jcenter() // Warning: this repository is going to shut down soon
      }
  }
  
  task clean(type: Delete) {
      delete rootProject.buildDir
  }
  </code></pre>
  <h1>build.gradle (App)</h1>
  <pre><code>plugins {
      id 'com.android.application'
      id 'kotlin-android'
      id 'kotlin-android-extensions'
  }
  
  apply plugin: 'com.google.gms.google-services'
  
  android {
      compileSdkVersion 30
  
      defaultConfig {
          applicationId &quot;com.marco.booking_app&quot;
          minSdkVersion 23
          targetSdkVersion 30
          versionCode 1
          versionName &quot;1.0&quot;
  
          testInstrumentationRunner &quot;androidx.test.runner.AndroidJUnitRunner&quot;
      }
  
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
          }
      }
      compileOptions {
          sourceCompatibility JavaVersion.VERSION_1_8
          targetCompatibility JavaVersion.VERSION_1_8
      }
      kotlinOptions {
          jvmTarget = '1.8'
      }
      buildFeatures {
          viewBinding true
      }
  }
  
  dependencies {
  
      implementation &quot;org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version&quot;
      implementation 'androidx.core:core-ktx:1.5.0'
      implementation 'androidx.appcompat:appcompat:1.3.0'
      implementation 'com.google.android.material:material:1.3.0'
      implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
      implementation 'androidx.legacy:legacy-support-v4:1.0.0'
      implementation 'androidx.lifecycle:lifecycle-livedata-ktx:2.3.1'
      implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.3.1'
      implementation 'androidx.annotation:annotation:1.2.0'
      testImplementation 'junit:junit:4.+'
      androidTestImplementation 'androidx.test.ext:junit:1.1.2'
      androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
      implementation platform('com.google.firebase:firebase-bom:28.1.0')
      implementation 'com.google.firebase:firebase-analytics-ktx'
      implementation 'com.google.firebase:firebase-auth-ktx'
  }
  
  </code></pre>
  <h1>Questions</h1>
  <ol>
  <li>What makes this error occur?</li>
  <li>How can I solve it?</li>
  </ol>