Quick answer
An accessible XML sitemap is a sitemap that the audit can fetch and parse as a valid urlset or sitemapindex. NOTABIS records sitemap-accessible as a passed check for each candidate that meets those conditions; it is a crawlability measurement, not a promise that listed URLs will be indexed. Keep the sitemap public, valid, and aligned with the URLs you want search engines to discover.
What the issue means
A sitemap is an XML document that lists URLs, or an index that points to other sitemaps. It gives search engines a useful discovery hint, especially for large, new, or internally complex sites. It does not replace contextual internal links, canonical signals, or a successful page response, and submitting one does not guarantee crawling or ranking.
Why it matters for SEO
When a sitemap can be retrieved and parsed, it provides another route to discover important pages and helps an auditor compare declared URLs with the crawl. An accessible file can still contain stale, duplicate, redirected, blocked, non-canonical, or non-HTML URLs. Treat accessibility as the first check, then review the contents and reconciliation evidence.
How NOTABIS detects it
NOTABIS collects sitemap locations declared in robots.txt and also probes the origin’s conventional /sitemap.xml and /sitemap_index.xml paths. For each candidate, it follows permitted redirects, requires a response below the HTTP error range, parses the XML, accepts the standard sitemap namespace when present, and requires a urlset or sitemapindex root. It then records a passed sitemap-accessible check.
The same pass can carry a separate sitemap-invalid-content-type issue when the body parses but the response does not advertise an XML content type. The check does not prove that every child sitemap or URL is complete, indexable, same-origin, or current.
How to check it yourself
Request the declared URL and inspect both headers and XML:
curl -sS -D - https://example.com/sitemap.xml -o sitemap.xml
head -n 5 sitemap.xml
Confirm a successful final response, an XML content type, the standard namespace when supplied, and a valid <urlset> or <sitemapindex>. Check that each <loc> is an absolute URL you intend to expose, and compare the list with canonical pages, redirects, noindex routes, and your internal links.
How to fix it
Generate the sitemap from the same source of truth as your public canonical URLs. Serve it at a stable public URL with an XML content type, correct namespace, and valid escaping. Split large files with a sitemap index when needed, update robots.txt and Search Console with the final location, and remove stale or private URLs. Fix the listed page responses as well; a valid sitemap does not make a 404 or noindex page indexable.
After publishing changes, fetch the final URL from an external network and rerun the audit. Search engines choose whether and when to fetch a sitemap, so the passed check is evidence of availability at audit time.
When this is intentional or does not need fixing
Small, well-linked sites may gain little from a sitemap, although a sitemap you have declared should remain reachable and accurate. A site can also use a sitemap index instead of a single URL-set file. Do not add private, duplicate, or temporary URLs simply to increase the sitemap count.
Related issues
Review sitemap unavailable, orphan pages, and missing canonical URLs. Google’s sitemap overview explains discovery and sitemap limits.
Run a NOTABIS audit
NOTABIS checks declared and conventional sitemap locations, records successful parses, and shows reconciliation evidence for the URLs those files contain.