protected override void OnException(ExceptionContext filterContext)
{
    if (filterContext != null)
    {
        var ex = filterContext.Exception ?? new Exception("Информация об исключении отсутствует.");

        filterContext.ExceptionHandled = true;

        if (ex is HttpException && (ex as HttpException).GetHttpCode() == 401)
        {
            filterContext.Result = AuthorizeRedirectAttribute.RouteResult;
            return;
        }

        var exeption = GetErrors(ex).Last();
        var data = new ErrorModel
        {
            ErrorMessage = exeption.Message, // string.Format("{0}\n{1}", exeption.Message, exeption.StackTrace),
            Exceptions = new[] { exeption },
        };

        filterContext.Result = View("ErrorPage", data);
    }
}

public IEnumerable<Exception> GetErrors(Exception exception)
{
    if (exception is DbEntityValidationException)
    {
        foreach (var validationErrors in (exception as DbEntityValidationException).EntityValidationErrors)
        {
            foreach (var validationError in validationErrors.ValidationErrors)
            {
                exception = new Exception(string.Format("{0}:{1}", validationError.PropertyName, validationError.ErrorMessage));
                break;
            }
        }
    }

    while (exception != null)
    {
        yield return exception;
        exception = exception.InnerException;
    }
}