System.ArgumentException was unhandled - Message=[net_WebHeaderInvalidControlChars]

WebClient를 사용하는 경우 웹 서버의 응답을 캐시하는 문제가 발생하는데요. 이에 대해서는 예전에 다음의 글에서도 비슷하게 언급한 적이 있습니다.

WCF REST 서비스 - 웹 브라우저 측 Ajax 호출 캐시
; https://www.sysnet.pe.kr/2/0/1049

WebClient wc = new WebClient();
wc.Headers[HttpRequestHeader.IfModifiedSince] = DateTime.UtcNow.ToString();

System.ArgumentException was unhandled
  Message=[net_WebHeaderInvalidControlChars]
Arguments:
Debugging resource strings are unavailable. Often the key and arguments provide sufficient information to diagnose the problem. See http://go.microsoft.com/fwlink/?linkid=106663&Version=4.7.60408.0&File=System.Net.dll&Key=net_WebHeaderInvalidControlChars 
Parameter name: name
  StackTrace:
       at System.Net.ValidationHelper.CheckBadWebHeaderChars(String name, Boolean isHeaderValue)
       at System.Net.WebHeaderCollection.set_Item(String name, String value)
       at System.Net.WebHeaderCollection.set_Item(HttpRequestHeader header, String value)
       at OfficeController.App.CallUrl(String url, DownloadStringCompletedEventHandler handler)
       at OfficeController.MainPage.btnConnectClicked(Object sender, RoutedEventArgs e)
       at OfficeController.MainPage..ctor()
       at System.Reflection.RuntimeConstructorInfo.InternalInvoke(RuntimeConstructorInfo rtci, BindingFlags invokeAttr, Binder binder, Object parameters, CultureInfo culture, Boolean isBinderDefault, Assembly caller, Boolean verifyAccess, StackCrawlMark& stackMark)
       at System.Reflection.RuntimeConstructorInfo.InternalInvoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, StackCrawlMark& stackMark)
       at System.Activator.InternalCreateInstance(Type type, Boolean nonPublic, StackCrawlMark& stackMark)
       at System.Activator.CreateInstance(Type type)
       at System.Windows.Navigation.PageResourceContentLoader.BeginLoad_OnUIThread(AsyncCallback userCallback, PageResourceContentLoaderAsyncResult result)
       at System.Windows.Navigation.PageResourceContentLoader.<>c__DisplayClass4.<BeginLoad>b__0(Object args)
       at System.Reflection.RuntimeMethodInfo.InternalInvoke(RuntimeMethodInfo rtmi, Object obj, BindingFlags invokeAttr, Binder binder, Object parameters, CultureInfo culture, Boolean isBinderDefault, Assembly caller, Boolean verifyAccess, StackCrawlMark& stackMark)
       at System.Reflection.RuntimeMethodInfo.InternalInvoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, StackCrawlMark& stackMark)
       at System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters)
       at System.Delegate.DynamicInvokeOne(Object[] args)
       at System.MulticastDelegate.DynamicInvokeImpl(Object[] args)
       at System.Delegate.DynamicInvoke(Object[] args)
       at System.Windows.Threading.DispatcherOperation.Invoke()
       at System.Windows.Threading.Dispatcher.Dispatch(DispatcherPriority priority)
       at System.Windows.Threading.Dispatcher.OnInvoke(Object context)
       at System.Windows.Hosting.CallbackCookie.Invoke(Object[] args)
       at System.Windows.Hosting.DelegateWrapper.InternalInvoke(Object[] args)
       at System.Windows.RuntimeHost.ManagedHost.InvokeDelegate(IntPtr pHandle, Int32 nParamCount, ScriptParam[] pParams, ScriptParam& pResult)

2013-09-26 오전 12:18:31

WebClient wc = new WebClient();
wc.Headers[HttpRequestHeader.IfModifiedSince] = DateTime.UtcNow.ToString(CultureInfo.InvariantCulture);