Copy Page Tree not working after Confluence update

Problem

After a major update, the Copy Page Tree is not working. The New Parent page options are not loading

Did you perform a major update from a Confluence version before 7.X.X?

There may be some issues with the index. Did you reindex after upgrading? How to rebuild the content indexes from scratch

Do you have custom HTML on your pages? (under General Configuration)

Check to see if you have any AJS calls. Some were depreciated between versions. Remove those calls, and the app should return functionality.