title: WCF - weird error
body: <p>I have my dll hosted at IIS with <code>wsHttpBinding</code>. I have this weird error happened intermediate.</p>
  
  <p>Well, everything will be restored back normal again when I reset the IIS (iisreset).</p>
  
  <p>I also read this one <a href="http://msdn.microsoft.com/en-us/library/ee517280.aspx" rel="nofollow">http://msdn.microsoft.com/en-us/library/ee517280.aspx</a>. But I am not sure it has to do with this. Please guide me if you more info on this. Thanks.</p>
  
  <blockquote>
    <h2>Server Error in '/MSBuildCompilation' Application.</h2>
    
    <p>Either a required impersonation level was not provided, or the
    provided impersonation level is invalid. (Exception from HRESULT:
    0x80070542)  Description: An unhandled exception occurred during the
    execution of the current web request. Please review the stack trace
    for more information about the error and where it originated in the
    code. </p>
    
    <p>Exception Details: System.Runtime.InteropServices.COMException: Either
    a required impersonation level was not provided, or the provided
    impersonation level is invalid. (Exception from HRESULT: 0x80070542)</p>
    
    <p>Source Error: </p>
    
    <p>An unhandled exception was generated during the execution of the
    current web request. Information regarding the origin and location of
    the exception can be identified using the exception stack trace below.</p>
    
    <p>Stack Trace: </p>
    
    <p>[COMException (0x80070542): Either a required impersonation level was
    not provided, or the provided impersonation level is invalid.
    (Exception from HRESULT: 0x80070542)]</p>
    
    <p>[FileLoadException: Could not load file or assembly
    'System.ServiceModel, Version=4.0.0.0, Culture=neutral,
    PublicKeyToken=b77a5c561934e089' or one of its dependencies. Either a
    required impersonation level was not provided, or the provided
    impersonation level is invalid. (Exception from HRESULT: 0x80070542)] 
    System.ServiceModel.Activation.HttpModule.ProcessRequest(Object
    sender, EventArgs e) +0<br>
    System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
    +148    System.Web.HttpApplication.ExecuteStep(IExecutionStep step,
    Boolean&amp; completedSynchronously) +75</p>
  </blockquote>