title: How to troubleshoot a TypeLoadException that doesn't specify a type?
body: <p>I have a Windows Phone 7.1 application that references a Windows Phone 7.1 library.  That library references a PCL which includes Windows Phone 7 or higher as a target.</p>
  
  <p>At one point, the application attempts to create a new instance of a class from the library which extends a class from the PCL.  The PCL class has a protected constructor, so I override it in the library class to make it public.  The constructor takes 1 parameter.  In the application I create an instance of this one parameter and pass it to the constructor in the library, which has no code of its own, just <code>: base()</code> to the other constructor.</p>
  
  <p>I run the app in the windows phone emulator and it's all going fine.  The app loads and I navigate through a few screens.</p>
  
  <p>I hit a breakpoint and step through.  I land in the library's constructor fine but then when I try to go one step further, which would be into the PCL's constructor, I just get a TypeLoadException that says "Failure has occurred while loading a type".  The stack trace stops at the library constructor and there is no inner exception.</p>
  
  <p>I've also tried the Windows Phone 7.8 emulator.  And I've also tried creating the new instance directly in the library class's constructor using a parameterless constructor and just saying <code>: base(new ...)</code> but it all fails the same way.</p>
  
  <p>I have no idea how to figure out what the problem is because I don't know what it might be trying to look for that's unavailable.  I see the library and the PCL assemblies listed in the manifest in the project's build directory.</p>
  
  <p>My google fu is coming up dry.  Anyone have any ideas where I might be able to continue looking?</p>
  
  <p>Thanks.</p>