question

I am getting these crash reports in the Google Play Crashes & ANRs, please advice, I am using Amazon ads 5.4.146: java.lang.Error: FATAL EXCEPTION [main] Unity version : 4.5.5p3 Device model : samsung SAMSUNG-SGH-I577 Device fingerprint: samsung/SGH-I577/SGH-I577:4.0.4/IMM76D/UCAMK1:user/release-keys Caused by: java.lang.NoClassDefFoundError: android/os/AsyncTask at android.webkit.WebView.setupPackageListener(WebView.java:2067) at android.webkit.WebView. (WebView.java:1773) at android.webkit.WebView. (WebView.java:1730) at android.webkit.WebView. (WebView.java:1719) at android.webkit.WebView. (WebView.java:1378) at android.webkit.WebView. (WebView.java:1369) at com.amazon.device.ads.WebViewFactory.createWebView(WebViewFactory.java:39) at com.amazon.device.ads.ViewManager.createWebView(ViewManager.java:146) at com.amazon.device.ads.ViewManager. (ViewManager.java:49) at com.amazon.device.ads.AdContainer.createViewManager(AdContainer.java:73) at com.amazon.device.ads.AdContainer.getViewManager(AdContainer.java:65) at com.amazon.device.ads.AdContainer.setViewHeight(AdContainer.java:129) at com.amazon.device.ads.AdController.setViewHeightToAdHeight(AdController.java:284) at com.amazon.device.ads.AdController.initialize(AdController.java:582) at com.amazon.device.ads.AdSlot.initializeAd(AdSlot.java:98) at com.amazon.device.ads.AdLoader.finalizeFetchAd(AdLoader.java:396) at com.amazon.device.ads.AdLoader$2.run(AdLoader.java:98) at android.os.Handler.handleCallback(Handler.java:605) at android.os.Handler.dispatchMessage(Handler.java:92) at android.os.Looper.loop(Looper.java:137) at android.app.ActivityThread.main(ActivityThread.java:4511) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:511) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:976) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:743) at dalvik.system.NativeStart.main(Native Method)