SEO finding
The lastmod dates in the sitemap do not match what changed on the pages
SEO Warning Severity: Low
Part of the audit The sitemap asks for indexing, the page refuses. Finding id: seo.sitemapLastmodUnreliable.
What it costs you
The sitemap protocol asks for the date the page was last modified, not the date the sitemap was generated. Dates that are all the same, or that move without a change, give a crawler no reason to believe any of them, so real updates are picked up later.
What to do
Write the date of the last real change of each page into lastmod, or leave lastmod out.
What it checks
- Sitemap date newer than any real change
- Same sitemap date on every page
How to fix it
Fill lastmod from the content's own change date
- Find where the sitemap is generated.
- Use the date the page content was last edited, not the time the file was built.
- If no such date is stored, leave lastmod out. A missing date does less harm than a wrong one.
How to check: Fetch the sitemap on two different days: lastmod only moves for pages that were edited.
A real case
Bing reported in February 2023 that lastmod values in sitemaps were set correctly in 79% of cases and wrongly in 18%, most often as the date the sitemap was generated instead of the date the page changed.
Thresholds
| Name | Default | Meaning |
|---|---|---|
min_entries | 10 | A sitemap needs at least this many dated entries before identical dates are reported. |
slack_days | 2 | Days a lastmod may be newer than the last change we saw before it is reported. |
How to verify by hand
Search Console sitemap report: submitted versus indexed.
What this relies on
The page state is deliberate and the sitemap is stale, unless most of a section is affected.