I have added validation rules on the server side using a partial class like it is explain in the videos. It works well on the Add page where the errors are shown in a notification.
But doing the same thing with Edit page, the errors don´t show up in the notification.
Using the DevTools I know the response is correctly sending the errors.
Using VS I have check the code and when in the service the call to the server is this:
return await httpClient.SendAsync(httpRequestMessage);
Where the return is not treated like an exception.
If I change the call to:
var response = await httpClient.SendAsync(httpRequestMessage);
return await response.ReadAsync();
Then the errors are shown correctly in the notification.