Do changes to Wordpress permalink custom structure affect old urls?

Question

Will changing WP permalink custom structure affect old posts URL?

For example. I have a large group of posts that follow this custom structure: /blog/%category%/%postname%/

I want to change it to /blog/

Or better yet, be able to manually add structure after the root domain for every post.

So that I have the option to manually enter /%category%/%postname%/

I'm hoping that changing my permalink custom structure will only affect new posts going forward and old posts remain unchanged.

Answer 1

Yes.

You may want to use a redirect plugin to setup redirect rules for your inactive urls.

Answer 2

Yes, absolutely. Upon clicking "Save" in the Permalinks page, a command is sent to the database to update the new URL structure.

It doesn't matter whether your URLs are active or inactive, if you change the permalink structure it is a "global" change and all single posts will follow that.

To give you a direct answer: All. New and Old URLs will be changed.