Didn't find class "com.google.firebase.provider.FirebaseInitProvider"
<p>Before, my program run well. But When I just updated my Android studio to the latest version (2.2 built on 15-sept-16), I am having the following error. When I built it, it says: Built sucessfully, but this error appears when I run my program:</p>

<blockquote>
  <p>E/AndroidRuntime: FATAL EXCEPTION: main                                                                            Process: com.example.androidtutorial, PID: 28293
  java.lang.RuntimeException: Unable to get provider
  com.google.firebase.provider.FirebaseInitProvider:
  java.lang.ClassNotFoundException: Didn't find class
  "com.google.firebase.provider.FirebaseInitProvider" on path:
  DexPathList[[zip file
  "/data/app/com.example.androidtutorial-2/base.apk"],nativeLibraryDirectories=[/data/app/com.example.androidtutorial-2/lib/x86,
  /system/lib, /vendor/lib]]
                                                                               at
  android.app.ActivityThread.installProvider(ActivityThread.java:5814)
                                                                               at
  android.app.ActivityThread.installContentProviders(ActivityThread.java:5403)
                                                                               at
  android.app.ActivityThread.handleBindApplication(ActivityThread.java:5342)
                                                                               at android.app.ActivityThread.-wrap2(ActivityThread.java)
                                                                               at
  android.app.ActivityThread$H.handleMessage(ActivityThread.java:1528)
                                                                               at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                               at android.os.Looper.loop(Looper.java:154)
                                                                               at android.app.ActivityThread.main(ActivityThread.java:6077)
                                                                               at java.lang.reflect.Method.invoke(Native Method)
                                                                               at
  com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
                                                                               at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
                                                                            Caused by: java.lang.ClassNotFoundException: Didn't find class
  "com.google.firebase.provider.FirebaseInitProvider" on path:
  DexPathList[[zip file
  "/data/app/com.example.androidtutorial-2/base.apk"],nativeLibraryDirectories=[/data/app/com.example.androidtutorial-2/lib/x86,
  /system/lib, /vendor/lib]]
                                                                               at
  dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
                                                                               at java.lang.ClassLoader.loadClass(ClassLoader.java:380)
                                                                               at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
                                                                               at
  android.app.ActivityThread.installProvider(ActivityThread.java:5799)
                                                                               at
  android.app.ActivityThread.installContentProviders(ActivityThread.java:5403) 
                                                                               at
  android.app.ActivityThread.handleBindApplication(ActivityThread.java:5342) 
                                                                               at android.app.ActivityThread.-wrap2(ActivityThread.java) 
                                                                               at
  android.app.ActivityThread$H.handleMessage(ActivityThread.java:1528) 
                                                                               at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                               at android.os.Looper.loop(Looper.java:154) 
                                                                               at android.app.ActivityThread.main(ActivityThread.java:6077) 
                                                                               at java.lang.reflect.Method.invoke(Native Method) 
                                                                               at
  com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
                                                                               at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)</p>
</blockquote>

<p>I already looked at other questions but the problem is not the same. 
What am I doing wrong? Please help</p>