How can I maintain a global list datasource? It has a bug now..like The content of the adapter has..

I got an issue reported in Xamarin Insights.

Java.Lang.RuntimeExceptionThe content of the adapter has changed but ListView did not receive a notification. Make sure the content of your adapter is not modified from a background thread, but only from the UI thread. Make sure your adapter calls notifyDataSetChanged() when its content changes. [in ListView(-1, class android.widget.ListView) with Adapter(class android.widget.HeaderViewListAdapter)]

I guess this on happens because my maintenance of a global datasource as a list view.
What i'm doing is have a list which is the datasource of a list in one page as the following:

partial class App : Application
    {
public static async void ProjectListRequest(Action callBack)
        {
            IProgressDialog service =  dialogService.Loading("Refreshing Projects....",null,"",true);
            WebResponse resp = await BaseHttpRequest.SendHttpRequest("api2/service/project/mobile/summaries");
            if (resp == null) {
                service.Hide();
                dialogService.Alert("Error","Refresh Failed","OK");
                return;
            }
            var serializer = new JsonSerializer();
            List<ProjectSumDto> projectListRet = new List<ProjectSumDto>();
            using (var sr = new StreamReader(resp.GetResponseStream()))
            {
                using (var jsonTextReader = new JsonTextReader(sr))
                {
                    JArray jObject = serializer.Deserialize(jsonTextReader) as JArray;
                    projectListRet = jObject.ToObject<List<ProjectSumDto>>();
                }
            }
            Device.BeginInvokeOnMainThread(()=>{
            if (App.ListViewItems.Count > 0) {
                App.ListViewItems.Clear ();
            }
            foreach (ProjectSumDto prj in projectListRet)
                App.ListViewItems.Add(prj);
                App.ListProject = projectListRet;
            });
            service.Hide();
            if (callBack != null)
                callBack ();
        }
}

For eg, I have page 1 which is a list like this:

Cell = new DataTemplate(typeof(CustomCell));
            App. ProjectListRequest(null); 
            listView.ItemsSource = App.ListViewItems;
            BindingContext = App.ListViewItems;
            listView.ItemTemplate = Cell;

every time when this page is load will do the code above. When in page 2 which is the detail page of page 1, I change the status of project and call this function again like this which will update the datasource of page 1 's list. I guess when this service is done or when user go back to page 1, then it crashes.

await Task.Run (() => App.ProjectListRequest (null));

The overall idea is just want to maintain a global datasource which I can update it in any pages not only in the page which is using it.