Addmob free Error Building app

Hello i’m getting this error while building my app , i don’t know why but i can’t build app i tried to use old version but it’s still not work
This is the error :

Dex: Error converting bytecode to dex: Cause: PARSE ERROR: class name (com/google/android/gms/base/R) does not match path (Com/google/android/gms/base/R.class) ...while parsing Com/google/android/gms/base/R.class

and this is my setting :

cli packages: (C:\Users\yahya\AppData\Roaming\npm\node_modules)

    @ionic/cli-utils  : 1.19.1
    ionic (Ionic CLI) : 3.19.1

global packages:

    cordova (Cordova CLI) : 4.0.0

local packages:

    @ionic/app-scripts : 3.1.8
    Cordova Platforms  : android 6.3.0
    Ionic Framework    : ionic-angular 3.9.2


    Android SDK Tools : 26.1.1
    Node              : v8.9.4
    npm               : 5.6.0
    OS                : Windows 10