title: Ghost error in Visual Studio - "missing definition" coming from nowhere
body: <p>I've got a windows store app which I've been working on for months now. </p>
  
  <p>This afternoon I tried to use visual studio remote debugger to test the app on an ARM tablet. I didn't get as far as the debugging stage, because my build threw the following error. </p>
  
  <pre><code>Error 153   'MyApp.Editor' does not contain a definition for 'OneDriveUpload_Click' 
              and no extension method 'OneDriveUpload_Click' accepting a first argument 
              of type 'MyApp.Editor' could be found (are you missing a using directive 
              or an assembly reference?)  
              C:\Users\Rory\Dropbox\MyApp\Editor.xaml 517 91  MyApp
  </code></pre>
  
  <p>When I double click this error in the error list, it takes me to line 517 of Editor.xaml:</p>
  
  <pre><code>&lt;MenuFlyoutItem Text="View HTML Source" Click="HTMLSource_Click" Style="{StaticResource MenuFlyoutItemStyle_HTML}" /&gt;
  </code></pre>
  
  <p>There was a reference to <code>OneDriveUpload_Click</code> here some weeks back, but it's long gone. I've done a search for <code>OneDriveUpload</code> throughout my solution and only got one hit for a piece of commented out code. </p>
  
  <p>Where the heck is this coming from? </p>
  
  <p>This is not the first "ghost" error I've seen. Every time my app fails to compile, for whatever reason, I also have the following two errors. </p>
  
  <pre><code>Error   151 The name "BasePrintPage" does not exist in the namespace "using:MyApp".
  </code></pre>
  
  <p>Except it definitely does:</p>
  
  <pre><code>namespace MyApp
  {
     public class BasePrintPage : Page
     { 
         ....
     }
  }
  </code></pre>
  
  <p>I also get an error telling me </p>
  
  <pre><code>Error   152 The member "BottomAppBar" is not recognized or is not accessible.   
  </code></pre>
  
  <p>If there are no other errors, the project compiles without issue, so these are not "real" errors. How do I get rid of them, and the one that's stopping me from compiling? </p>
  
  <p>EDIT: Just thought I'd add that deleting the SUO file has no effect on these issues. </p>