Aperture: Page turns white in Stock Black Book

If you are working with a Stock Book Black in Edit Layout mode, it's possible to select the black background and delete it, leaving a white page behind (this won't happen when in Edit Content mode). If you do this accidentally, the quickest fix is to select Edit > Undo before going any further. If you're too far gone to use Undo, you have two different options for fixing it.

For any page other than the cover, you can select the page in the Pages pane, then click the black triangle next to it for the list of page templates. Choose any template that is different from the currently selected template, then switch back to the desired template. This will cause you to have to replace the art and/or text on this page, but it won't affect the rest of the book.

However, this method won't work if you've done this to the cover, because there is no alternate template for the cover. In this event, use method 2:

1. Make note of any unique text you've entered throughout the book, because you may lose some of it (particularly captions).
2. Click the Theme button (just above the Pages pane), immediately to the left of "Theme: Stock Book Black".
3. When you see the "Switching Themes" warning, click OK.
4. Select Stock Book from the list of themes, and click Choose Theme.
5. Repeat steps 3 and 4, except that this time you'll switch back to Stock Book Black.
6. Replace images and/or text on the page that was affected, and check all other pages for text (particularly captions) that may have been lost in the theme switch.