The app icon set "AppIcon" has an unassigned child
<p>I clean built my app and see this error message: The app icon set "AppIcon" has an unassigned child.</p>

<p>When I view Images.xcassets every icon slot is filled with the correct icon and there are no unassigned icons. In the past XCode seemed to randomly forget the slot for an icon and put it underneath all the labeled icon slots. On those occasions I dragged the icon back to the correct slot and the error went away. There are also no errors about any Icons being the wrong size.</p>

<p>I checked Images.xcassets/AppIcon.appiconset/Contents.json and there are no entries in the JSON that have a blank filename.</p>

<p>I'm using XCode 7.2.</p>

<p>I would appreciate any help.</p>