Right a fully flushed out SaveChanges that will show the error message if EndSaveChanges() fails, like the code sample below. Obviously you can't use the console to write out your message in silverlight, but you get the idea.
For instance, when I wrote the following sample, I found that I was getting a forbidden error, because my entity set had EntitySetRights.AllRead, not EntitySetRights.All
class Program
{
private static AdventureWorksEntities svc;
static void Main(string[] args)
{
svc =
new AdventureWorksEntities(
new Uri("http://localhost:5068/AWDataService.svc",
UriKind.Absolute));
var productQuery = from p in svc.Products
where p.ProductID == 740
select p;
var product = productQuery.First();
ShowProduct(product);
product.Color = product.Color == "Silver" ? "Gray" : "Silver";
svc.UpdateObject(product);
svc.BeginSaveChanges(SaveChangesOptions.Batch, OnSave, svc);
ShowProduct(product);
Console.ReadKey();
}
private static void ShowProduct(Product product)
{
Console.WriteLine("Id: {0} Name: {1} Color: {2}",
product.ProductID, product.Name, product.Color);
}
private static void OnSave(IAsyncResult ar)
{
svc = ar.AsyncState as AdventureWorksEntities;
try
{
WriteResponse(svc.EndSaveChanges(ar));
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
}
private static void WriteResponse(DataServiceResponse response)
{
if(response.IsBatchResponse)
{
Console.WriteLine("Batch Response Code: {0}", response.BatchStatusCode);
}
foreach (ChangeOperationResponse change in response)
{
Console.WriteLine("Change code: {0}", change.StatusCode);
if(change.Error != null)
{
Console.WriteLine("\tError: {0}", change.Error.Message);
}
}
}
}