After the migration: every 404 found, mapped and redirected

The job

Every migration leaks: renamed slugs, moved categories, dropped pages. The rankings leak with them until the 301 map exists. NibWP reads the 404 log, compares old and new URL sets, proposes the map, flags chains before they're created, and fixes the internal links that point at dead URLs.

It works with the Redirection plugin or your SEO plugin's redirects — whichever the site runs.

The prompts, exactly as you'd type them

Plain English is the interface. These are real prompts for this job — copy them, swap in your own names, and adjust in conversation.

Find the damage

Compare the old sitemap [paste or URL] with the current site. List URLs that now 404, with their best new match and a confidence level.

Build the map

Create 301s for every confident match. Show me the map first and flag anything that would chain. List the uncertain ones for my decision.

Fix the sources

Find internal links still pointing at the old URLs and update them to the new ones — plan first.

The process — what actually happens

Every write follows the same shape: the agent reads before it writes, shows you a plan, and nothing lands without your approval. The audit log records every call.

1. The crawl plus the 404 log establish what's actually broken and how often it's hit.
2. Redirects are created through the plugin — grouped, chain-checked, one hop.
3. Internal links get updated at the source so the redirects carry only external traffic.
4. Uncertain matches come to you as a short decision list, not a spreadsheet.
5. Re-run the crawl after — the report shows zero leaks or exactly what's left.

The tools this uses

Runs on the Redirection integration (or your SEO plugin's redirects) plus core tools:

• nibwp/redirection-* — redirects, groups, the 404 log
• Broken-link crawl across the site
• nibwp/wp-update-post — internal links fixed at the source

The outcome

The leak stops the week of the migration instead of months later. Full walkthrough in the 404 guide.

Related solutions

Guide: fix 404s after a WordPress migration · SEO at scale.