The symptom is specific: the sitemap lists pages that no longer exist. Start with the affected item and identify the decision or input that could produce this behavior.
Find the likely cause
Generation uses an outdated content inventory.
Treat this as an explanation to verify against the actual work. Look at the input, the relevant decision, and the final result together. If the evidence does not support this diagnosis, investigate the mismatch before applying a convenient but unrelated fix.
Make the targeted correction
Rebuild from current published records and remove invalid entries.
A sitemap is most useful when it accurately lists the site's intended discoverable canonical pages.
Check that the repair worked
Fetch a sample and investigate every failed URL pattern.
Repeat the check on the final version that the reader or customer will encounter. An approved draft, a preview, and a published result can differ; the acceptance decision should concern the version people actually use.
Prevent the next related failure
A separate issue to watch for is this: important new articles never reach the sitemap. Include the correct content type and refresh the sitemap after publication.
Monitor the useful outcome
Track invalid entries, missing intended pages, and consistency between sitemap URLs and site behavior.
Keep a short record of the original symptom, the evidence behind the diagnosis, and the result of the acceptance check. That record makes the solution reusable when the same condition appears again, without assuming that every superficially similar problem has the same cause.
Official reference for the platform or standard discussed: Google Search Central: sitemaps.