In this particular case, the issue was caused by an invalid reference to the Background.png image in the WMAppManifest.xml file. The reference to the image was still there, but the image had been removed from that referenced location/folder. So in this case, I just simply needed to copy the Background.png back in to the project folder, and it’s good to go. The other way to correct it, is to remove the reference to the image from the appropriate folder in Solution Explorer. Make sure to set your images to Content, and Copy Always.