For those that had an issue with the SEO 1.7.3 update, where after updating the in-app link to the XML Sitemap was returning a 404 error, which was confirmed by Google Webmaster, note the following in my case, which fixed the problem for me. I had two other plugins that I updated at the same time, one of which was the latest WooCommerce plugin. I deactivated then reactivated both of the other plugins after which the SEO plugin worked properly and the XML Sitemap was no longer returning a 404 error. I hope this helps.
thegrape.com
WordPress v4.1
WooCommerce v2.3.4
Legenda theme v2.5 by 8 Themes
