title: Exception thrown at 0x00007FF93E507A7A (ntdll.dll) .Access violation reading location 0xFFFFFFFFFFFFFFFF
body: <p>I'm using POCO lib to working network. 
  i use JSON data of POCO/JSON . my code:</p>
  
  <pre><code>User user(context.marshal_as&lt;std::string&gt;(tbUserName-&gt;Text),
          context.marshal_as&lt;std::string&gt;(tbFullName-&gt;Text),
          context.marshal_as&lt;std::string&gt;(tbDisplayName-&gt;Text),
          context.marshal_as&lt;std::string&gt;(tbEmail-&gt;Text),
          context.marshal_as&lt;std::string&gt;(tbPhoneNumber-&gt;Text),
          context.marshal_as&lt;std::string&gt;(tbNamSinh-&gt;Text),
          context.marshal_as&lt;std::string&gt;(tbPassword-&gt;Text),
          context.marshal_as&lt;std::string&gt;(tbConfirm-&gt;Text)
      );
      string jsonString = user.serialize();
  </code></pre>
  
  <p>I have an error Exception thrown at <code>0x00007FF93E507A7A</code> (<code>ntdll.dll</code>) in Client_Winform.exe:</p>
  
  <blockquote>
    <p>0xC0000005: Access violation reading location 0xFFFFFFFFFFFFFFFF.</p>
  </blockquote>
  
  <p>If there is a handler for this exception, the program may be safely continued.</p>