The main purpose of Permalink Manager is to allow WordPress users to edit the permalinks. As you may know, the URL changes may lead to 404 (“not found”) error. To prevent this from happening, the plugin will automatically redirect the old permalinks.
Canonical redirect in Permalink Manager
The canonical redirect is enabled by default. The main purpose of this feature is to redirect from original (native) to canonical permalinks. In other words, WordPress tries to “correct” the requested URL and send a visitor to the actual URL address.
It could be helpful, after you use Permalink Manager to adjust permalinks. The plugin will redirect a visitor trying to access old URL to new address.
Old slug redirect
“Old slug redirect” works in a similar manner to canonical redirect. Old slug redirect is used to provide a fallback for old slugs. Shortly, every time you change the slug, WordPress will save its previous version as a custom field ( _wp_old_slug).
If you turn “Old slug redirect” on, the function will check if requested slug is linked to any post. If it is, WordPress will trigger redirect to the correct permalink.
You can deactivate both “Canonical redirect” and “Old slug redirect” in Permalink Manager settings. These functionalities are available also in free version of plugin (Permalink Manager Lite).
Old custom permalinks redirect
The redirect may be also needed if you would like to change the custom permalink again. Permalink Manager will automatically redirect also all previous permalinks. The plugin will save the old permalinks as custom redirects. It will happen, eg. if you edit the custom permalink using URI Editor or Regenerate/reset tool.
To disable this functionality, please unselect “Old custom permalinks redirect” in the plugin settings.
Edit old custom permalinks redirects
Concurrently, you can adjust or remove the old-permalink redirects using URI Editor. You can find more detailed instructions on how to manage the custom redirects in this article.