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POWebClient error when using a thread in .NET
 

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  1. POWebClient error when using a thread in .NET
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    <p>I'm having a <strong>very</strong> weird error using the WebClient class in .NET 4.</p> <p>The app simply downloads some files off the internet and provides output on a textbox (the GUI is WPF). The method that does this is the following:</p> <pre><code>void DownloadFiles(object files) { var fileL = (List&lt;string&gt;) files; foreach (string url in fileL) { byte[] data; using (var k = new WebClient()) { data = k.DownloadData(url); } //Bunch of irrelevant code goes here... } } </code></pre> <p>(I added the using while trying to divine [yes I'm that desperate/ignorant] a solution, the problem happens even if the webclient is declared and initialized outside the foreach loop)</p> <p>Now the problem appears only when I'm executing this method on a thread separate from the WPF UI main thread. If it is executed on the UI thread then it works perfectly. When a new thread is created with:</p> <pre><code>Thread t = new Thread(DownloadFiles); t.Start(files); </code></pre> <p>The first time the code goes into the loop it will work, but when its the second pass inside the loop, I will always receive a TargetParameterCountException.</p> <p>I can't make any sense of this error. Any help is very much appreciated.</p> <p><strong>edit</strong> Here are the Exception Details:</p> <pre><code>Exception.Message = "Parameter count mismatch." Exception.InnerException = null Exception.Source = " mscorlib" </code></pre> <p>The StackTrace follows:</p> <pre><code>at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks) at System.Delegate.DynamicInvokeImpl(Object[] args) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs) at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler) at System.Windows.Threading.DispatcherOperation.InvokeImpl() at System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(Object state) at System.Threading.ExecutionContext.runTryCode(Object userData) at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData) at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Windows.Threading.DispatcherOperation.Invoke() at System.Windows.Threading.Dispatcher.ProcessQueue() at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean&amp; handled) at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean&amp; handled) at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs) at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler) at System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs) at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam) at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG&amp; msg) at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame) at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame) at System.Windows.Threading.Dispatcher.Run() at System.Windows.Application.RunDispatcher(Object ignore) at System.Windows.Application.RunInternal(Window window) at System.Windows.Application.Run(Window window) at System.Windows.Application.Run() at FileDownloader.App.Main() in d:\mis documentos\visual studio 2010\Projects\OneMangaDownloader\FileDownloader\obj\x86\Debug\App.g.cs:line 0 at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args) at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args) at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() at System.Threading.ThreadHelper.ThreadStart_Context(Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ThreadHelper.ThreadStart() </code></pre>
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    1. PTQuestion
    1. USabatishchev
    1. USCarlos G.
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    1. COPlease post more details on the error (message, stacktrace, InnerException details...)
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      1. POWebClient error when using a thread in .NET
      1. USThomas Levesque
    2. COAdded the info you requested Thomas, thx for any help
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      1. POWebClient error when using a thread in .NET
      1. USCarlos G.
 

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