GAE code not working

Question

The server login which was working yesterday not working saying below error

com.we.wegaurd.manager.UserManager doUserLogin: com.we.wegaurd.manager.UserManagerdoUserLogin() :: exception : (UserManager.java:1248) com.google.apphosting.api.ApiProxy$UnknownException: An error occurred for the API request datastore_v3.RunQuery(). at com.google.apphosting.utils.runtime.ApiProxyUtils.statusException(ApiProxyUtils.java:209) at com.google.apphosting.utils.runtime.ApiProxyUtils.getRpcError(ApiProxyUtils.java:130) at com.google.apphosting.runtime.ApiProxyImpl$AsyncApiFuture.setRpcError(ApiProxyImpl.java:632) at com.google.apphosting.runtime.ApiProxyImpl$AsyncApiFuture.failure(ApiProxyImpl.java:618) at com.google.apphosting.runtime.http.HttpApiHostClient.communicationFailure(HttpApiHostClient.java:203) at com.google.apphosting.runtime.http.JettyHttpApiHostClient$Listener.onComplete(JettyHttpApiHostClient.java:167) at org.eclipse.jetty.client.ResponseNotifier.notifyComplete(ResponseNotifier.java:193) at org.eclipse.jetty.client.ResponseNotifier.notifyComplete(ResponseNotifier.java:185) at org.eclipse.jetty.client.HttpExchange.notifyFailureComplete(HttpExchange.java:269) at org.eclipse.jetty.client.HttpExchange.abort(HttpExchange.java:240) at org.eclipse.jetty.client.HttpConversation.abort(HttpConversation.java:141) at org.eclipse.jetty.client.HttpRequest.abort(HttpRequest.java:735) at org.eclipse.jetty.client.HttpDestination.abort(HttpDestination.java:271) at org.eclipse.jetty.client.PoolingHttpDestination.failed(PoolingHttpDestination.java:81) at org.eclipse.jetty.client.DuplexConnectionPool$1.failed(DuplexConnectionPool.java:159) at org.eclipse.jetty.util.Promise$Wrapper.failed(Promise.java:84) at org.eclipse.jetty.client.HttpClient$1$1.failed(HttpClient.java:588) at org.eclipse.jetty.client.AbstractHttpClientTransport.connectFailed(AbstractHttpClientTransport.java:152) at org.eclipse.jetty.client.AbstractHttpClientTransport.connect(AbstractHttpClientTransport.java:141) at org.eclipse.jetty.client.HttpClient$1.connect(HttpClient.java:593) at org.eclipse.jetty.client.HttpClient$1.succeeded(HttpClient.java:570) at org.eclipse.jetty.client.HttpClient$1.succeeded(HttpClient.java:563) at org.eclipse.jetty.util.SocketAddressResolver$Async.lambda$resolve$1(SocketAddressResolver.java:181) at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:671) at org.eclipse.jetty.util.thread.QueuedThreadPool$2.run(QueuedThreadPool.java:589) at java.lang.Thread.run(Thread.java:748) Caused by: java.nio.channels.ClosedSelectorException at sun.nio.ch.SelectorImpl.keys(SelectorImpl.java:68) at org.eclipse.jetty.io.ManagedSelector.size(ManagedSelector.java:104) at org.eclipse.jetty.io.SelectorManager.chooseSelector(SelectorManager.java:190) at org.eclipse.jetty.io.SelectorManager.connect(SelectorManager.java:207) at org.eclipse.jetty.client.AbstractHttpClientTransport.connect(AbstractHttpClientTransport.java:118) ... 7 more

I am not sure if there are any lib issues. Can any one help me?