Sitemap or llms.txt returns 404.

Cause

WordPress rewrite rules were flushed by another plugin, a permalink change, or were never registered after a file-upload deploy. The sitemap and llms.txt endpoints depend on those rules.

Fix

1. Go to Settings → Permalinks in your WordPress admin.
2. Click Save Changes. No need to change anything. This re-flushes the rewrite rules.
3. Reload yoursite.com/sitemap.xml or /llms.txt.

Still 404? Deactivate and reactivate SEO & Chill. Activation re-registers the rules.

Good to know

llms.txt has a built-in fallback that serves the file directly from the request even when rewrite rules are broken, so in most cases it heals itself. The permalink save fixes the root cause.