I just switched my Permalinks Settings from "Numeric" to "Day and Name"
This has resulted in all URL's that point to posts that were published when I still had "Numeric" enabled coming back as "Page not Found."
The post is still there but it's URL has been switched. Since I am worried that all of these "Page Not Found" errors will result in loss of Google PageRank as well as a loss of traffic, I'm wondering if there is a way to fix this issue.
Preferably there would be a way to have those old "Numeric" URL's point to the new ones through a redirect or something.