Did you receive the ‘paper size not matching’ error when trying to change an existing page template in your notebook? If so, do take note that currently you can select only the pages that match to the size of your existing page.
This is because we now support multiple page sizes in NS2, it is not possible to scale the notes already existing on the current page to a new sized page. Hence, we had to limit these options. You can however use the ‘Add new page from template’ option via the Plus icon to add a fresh new page template of any type without any such restrictions.