Fatal Exception: java.lang.IllegalStateException: Only fullscreen activities can request orientation
       at android.os.Parcel.readException(Parcel.java:1953)
       at android.os.Parcel.readException(Parcel.java:1891)
       at android.app.IActivityManager$Stub$Proxy.setRequestedOrientation(IActivityManager.java:5683)
       at android.app.Activity.setRequestedOrientation(Activity.java:6121)
       at lka.b(SourceFile:140)
       at llx.a(SourceFile:211)
       at amqc.run(SourceFile:3)
       at android.os.Handler.handleCallback(Handler.java:808)
       at android.os.Handler.dispatchMessage(Handler.java:101)
       at android.os.Looper.loop(Looper.java:166)
       at android.app.ActivityThread.main(ActivityThread.java:7425)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:245)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:921)

//android O fix bug orientation
if (android.os.Build.VERSION.SDK_INT != 26) {
     setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
}

<activity
        android:name=".MainActivity"
        android:screenOrientation="portrait">
    </activity>