Try to redirect 404 to new/right URL, using the URI segments to find the right page. When a page is found 301 redirect to that page.
MP smart redirect: Simple 404 redirecter, without entering 404 pages and redirects! Download Now
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Originals Link WordPress.org
How to Install MP smart redirect: Simple 404 redirecter, without entering 404 pages and redirects! Plugin, Manually
Simple plugin to redirect your old URL’s that give a 404 to their new URL. For example: you deleted some categories and changed the permalink structure -> WordPress isn’t redirecting your posts to the right page and gives a 404, your old URL was dead-category/my-page.html and it’s now /my-page.html. This plugin fixes this issue and creates a 301 redirect to your right url. We don’t save any data to your database! So we also don’t create logs of your 404’s. You can use a different plugin for that like Redirection (recommended to install since you can view and add redirections this plugin might missed).
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