Currently I'm using this permalink structure: mywebsite.com/%postname%.html I want to change it to: mywebsite.com/%category%/%postname%/
When I do this, new links works fine, but the problem is, links to old posts, like mywebsite.com/some-old-post.html does not redirect to mywebsite.com/post-category/some-old-post/
I've read that WordPress is supposed to figure the new URL out automatically when the slug (some-old-post) stays intact, but in my case, it just goes to a 404 page.
Any idea how to fix this?
Thanks