Sitemap has no lastmod dates
What it is
No <url> entry in this sitemap has a <lastmod> element. <lastmod> is the optional date, and optionally the time, when the page’s content last changed in a meaningful way, written in W3C Datetime format such as 2026-09-01 or 2026-09-01T09:30:00+00:00.
Why it matters
Crawlers use lastmod to decide what to fetch again. Google uses it when it is consistently accurate, and Bing says it affects how quickly updates reach its search results and AI generated answers. Without it, an updated page waits for the crawler’s next routine visit, so refreshed content can take longer to show.
How Asky checks it
Asky reads each sitemap it uses during its daily site discovery and at the start of each technical audit. It is reported when a <urlset> lists at least one page and none of its entries has a <lastmod>. A single dated entry is enough to pass. Sitemap index files and plain-text sitemaps, which have no place for a date, are not checked. The dates are not judged here: a sitemap whose dates are all old raises the stale lastmod issue instead. <changefreq> and <priority> are not checked, since Google and Bing both ignore them.
Reported as an opportunity with low severity.
How to fix it
- Turn on lastmod in your sitemap generator or SEO plugin. Most CMS sitemaps can include it.
- Use the date the page’s main content, structured data or links last changed, not the time the sitemap was generated or a copyright year. On a headless site, map it to the document’s last content update.
- Do not stamp every entry with today’s date. Bing may disregard lastmod values that always match the current date.
- If every page really last changed more than a year ago, the stale lastmod issue follows once the dates are in; its page explains when that is fine.
- To leave it as it is: if your platform cannot write accurate dates, leaving lastmod out is better than wrong ones; mark the issue resolved.
Example
An entry on https://example.com/sitemap.xml before and after lastmod is enabled:
<!-- Before -->
<url><loc>https://example.com/blog/pricing-guide</loc></url>
<!-- After -->
<url>
<loc>https://example.com/blog/pricing-guide</loc>
<lastmod>2026-08-14T10:05:00+00:00</lastmod>
</url>