404 Errors Caused by Unscoped Rewrite Rule – Bugfix Report + Real Solutions

Hi there,

I’d like to share a bugfix report for WP myLinks—this is more than just a bug report; it includes root-cause analysis, how I diagnosed it, a working patch, and recommendations for both users and the plugin author.

1. Environment

• WordPress: 6.8.1
• Theme: Custom child theme (patch-child-master)
• Permalink structure: /post-name/

2. The Problem

As soon as WP myLinks is activated (even after flushing permalinks via Settings → Permalinks → Save), any two-segment URL on the site returns a 404. Examples:

/article/example-post/          → 404
/product/sample-product/        → 404
/category/news/                 → 404
/parent/child-page/             → 404
/custom-cpt/some-slug/          → 404

Resaving permalinks or clearing cache does not fix it.

3. Root Cause Analysis

Using Rewrite Rules Inspector, I discovered that WP myLinks registers an unscoped rewrite rule:

[^/]+/([^/]+)/?$    → index.php?attachment=$matches[1]   (source: mylink)

Because this regex:

• Is extremely broad (matches any two-segment path)
• Is injected at the top of the rewrite stack

WordPress never reaches more specific rules (page, single, product, or custom post-type rules), so everything 404s.

4. How I Diagnosed It

1. Activated WP myLinks → visited any two-segment URL → got 404
2. Installed Rewrite Rules Inspector
3. Tested /article/improve-interactions/ → saw the unscoped rule at the top
4. Deactivated WP myLinks → all URLs worked again
5. Confirmed it was not just a missing permalinks flush

5. Immediate Fix (for Users)

Place this small plugin in wp-content/mu-plugins/mylink-rewrite-fix.php, to scope the CPT slug and eliminate the conflict:

<?php
/**
 * MU Plugin: Scope WP myLinks CPT under your hub page slug
 */
add_filter( 'register_post_type_args', function( $args, $post_type ) {
    if ( $post_type === 'mylink' ) {
        $args['rewrite'] = [
            'slug'       => 'your-hub-slug',  // e.g. 'links', 'resources', etc.
            'with_front' => false,
            'feeds'      => false,
            'pages'      => false,
        ];
    }
    return $args;
}, 10, 2 );

1. Replace 'your-hub-slug' with the slug of your hub page.
2. Flush permalinks (Settings → Permalinks → Save).
3. Clear any caches.

Result:

• All WP myLinks URLs live under /your-hub-slug/.../
• All other two-segment URLs resolve normally

6. Recommendations for the Plugin Author

1. Use the user’s hub-page slug as the rewrite base
   – If the plugin lets the user designate a “MyLinks” page, automatically read its slug and apply it to the CPT rewrite.
2. Provide a “Link Base Slug” setting in the UI
   – Allow admins to change the base without custom code.
3. Avoid unscoped root-level regex
   – Only generate rewrite rules under that base slug; never use a catch-all two-segment pattern.

Implementing these changes would prevent this critical 404 issue on sites with any other two-level URLs.

Thanks for your work on WP myLinks—this plugin has great potential for managing a link hub, and I hope this report and patch help make it rock-solid. Let me know if you need any further details or testing!

• This topic was modified 12 months ago by Alex De Py.
• This topic was modified 12 months ago by Alex De Py.
• This topic was modified 12 months ago by Alex De Py.
• This topic was modified 12 months ago by Alex De Py.
• This topic was modified 12 months ago by Alex De Py.
• This topic was modified 12 months ago by Alex De Py.