title: Failed to load toolbox item. It will be removed from the toolbox
body: <p>I have a <code>WinForm</code> application. I also have created my own <code>User Control</code> for it. Everything worked fine. Until today that I received the error message when I try to add it back to my program (I never removed it. Visual Studio did).</p>
  
  <blockquote>
    <p>Failed to load toolbox item #UserControlName. It will be removed from
    the toolbox.</p>
  </blockquote>
  
  <p>I have it in my solution explorer but it vanishes from my toolbox after this error.
  I also receive the warning that says:</p>
  
  <blockquote>
    <p>'#UserControlName' is never assigned to, and will always have its
    default value null.</p>
  </blockquote>
  
  <p>And when I look at my designer code, that is true. But I haven't done anything with my designer code. My user control is defined there but not instantiated. How can I put it back?</p>
  
  <p>Does it have anything to do with the fact that I changed my build platform from <code>x32</code> to <code>x64</code>? If that is the case I will be surprised because the program was working fine after that change.</p>