A Google employee John Muller confirmed on Twitter that the search engine could ignore Sitemap.xml files if they contain invalid URLs. At the same time, if the URLs were redirected and the content is loaded, then this will not happen. Otherwise, Google will suspend URL retrieval.
“We will stop extracting Sitemaps if the URL is invalid, but if you return content or redirect (which is recommended), we will continue our attempts. However, this should not be a problem, as a whole Sitemap is just a tiny part of all the URLs that we extract from the site, ”explained Muller.
✔@VorticonCmdrAnswer to user@JohnMu
The sitemap files themselves. The HTTP-URLs are accessed nearly as often as the HTTPS.
We’d stop fetching sitemap files if the URLs are invalid, but if you’re returning content or redirecting (which is kinda recommended), we’ll keep trying them. It shouldn’t cause problems, since overall sitemap files are only a tiny-tiny part of all URLs fetched from a site.
6Recall that Google uses XML Sitemap data to determine canonical URLs, but this is a less significant signal than the rel = canonical attribute.