With a space level redirect in place for a phased migration to a new instance, "pretty URL title" pages redirect as expected and most "pageID title" pages were fixed to generate a "pretty URL title" before migration. However, some were missed and old links fail (that is, a "pageID title" page redirect ends in a "page not found" error in the new instance.
Is there a way to stop the redirect during it? For example, in the given time window the user can enter a command to remain in the old instance. This could allow a manual title fix on both instances to make the redirect work, such as replacing "&" with "and".