Steps to reproduce:

1. On Instance A (tested on Confluence 2.8.2), create a child page under the "Home" page
2. Upgrade Instance A to Instance B (an instance of Confluence 2.9) by pointing the Confluence Home Directory to Instance A's existing Home Directory
3. On Instance B, edit the child page created in Step 1
4. In the Edit Mode, try to move the page to another location

The current page is not highlighted. Manually select the current page in the page tree will yield the cancel icon. Hence, page cannot be moved.

In Firefox, a Javascript error will be returned in the console when the page tree is being rendered:

Error: AJS.PageOrdering.node is null
Source File: http://localhost:8297/s/1415/1/1.0/_/download/resources/confluence.web.resources:page-location-editor/page-location.js
Line: 31

The same problem cannot be reproduced if upgrade is done through Backup and Restore method.