Wordpress stands as one of the most popular content management systems (CMS) globally, thanks to its flexibility and user-friendly interface. One of its key features is the ability to customize the URL structure, also known as permalinks. However, setting up permalinks correctly can be a bit challenging, especially when working with custom post types. Some users encounter an issue where, after changing the permalink structure, some links start returning a 404 error, indicating that the requested page was not found. This article will guide you through steps to resolve this problem.

Root Cause of the Issue

404 errors typically occur when WordPress fails to properly map a request to a URL to existing posts or pages. With custom post types, this could be due to an incorrect or missing rewrite rule that wasn’t properly refreshed or updated after changing permalinks.

How to Resolve the Issue

1. Check Permalink Settings: The first step is to verify that your permalink settings are configured correctly. Navigate to Settings > Permalinks in your WordPress admin panel and ensure that the permalink structure is set according to your needs. After making changes, don’t forget to save the settings, which will automatically generate new rewrite rules.

2. Update Rewrite Rules: After changing permalinks, it’s crucial to manually flush and regenerate rewrite rules. You can do this either by simply saving the permalink settings (as mentioned above) or by using a plugin designed to regenerate rewrite rules.

3. Utilize Custom Post Type Functions: Ensure that your custom post type definitions correctly utilize the rewrite argument. This argument allows you to specify how rewrite rules should be created for a given post type. For example:

   'rewrite' => array('slug' => 'my-custom-type', 'with_front' => false),
   

   This code ensures that all links for the custom post type will use /my-custom-type/ as the base slug.

4. Reset Your Permalinks: Sometimes, resetting your permalinks may be necessary to resolve the issue. You can do this by changing the permalink structure to "Plain" and then setting it back to your desired structure. This process helps WordPress regenerate the rewrite rules.

5. Check for Plugin and Theme Conflicts: In some cases, 404 errors may be related to conflicts between plugins or with the current theme. You can diagnose the issue by deactivating all plugins and switching to a default WordPress theme (e.g., Twenty Twenty-One) and then gradually reactivating individual plugins and testing permalinks again.

404 errors caused by permalink settings for custom post types can be frustrating, but in most cases, they are easily fixable. The key to success lies in systematic debugging and testing, which will help identify and address the underlying cause of the problem. With these tips, you should be able to ensure that your website is fully functional again without any 404 errors.