if (!ModelState.IsValid)
{
  var sb = new System.Text.StringBuilder();
	
	 Dictionary<string, IEnumerable<Exception>> errorList = ModelState.ToDictionary(
		kvp => kvp.Key,
		kvp => kvp.Value.Errors.Select(e => e.Exception)
	);
	 sb.AppendLine("Exceptions:");

	foreach (string key in errorList.Keys)
	{
		foreach (Exception ex in errorList[key])
		{
            		if (ex != null)
            		{
			    sb.AppendFormat("{0}: {1} - [{3}]{2}", key, ex.Message, Environment.NewLine, ex.StackTrace);
            		}
		}
	}

	sb.AppendLine("Validation:");
	Dictionary<string, IEnumerable<string>> errorMessages = ModelState.ToDictionary(
		kvp => kvp.Key,
		kvp => kvp.Value.Errors.Select(e => e.ErrorMessage)
	);

	foreach (string key in errorMessages.Keys)
	{
		foreach (string message in errorMessages[key])
		{
			sb.AppendFormat("{0}: {1}{2}", key, message, Environment.NewLine);
		}
	}

	throw new Exception(sb.ToString());
}