At the end of June Google announced that it is retiring its sitemap ping: the address you could call to tell Google that your sitemap had changed. Google says most of the pings it received were spam, and the ping will stop working within six months.
What to do instead:
- Submit your sitemap once in Google Search Console. Google checks it again by itself.
- Add a Sitemap: line with the address of your sitemap to your robots.txt.
In the same announcement Google repeated how it reads the optional tags in a sitemap: it ignores <priority> and <changefreq>, and it uses <lastmod> only when the dates are consistently accurate. Other search engines may still use them, so there is no harm in keeping them.
If you use automatic upload with the Google ping switched on in your site settings, nothing breaks: your sitemap is still uploaded as before. Once Google switches the ping off, that ping simply has no effect any more.