Hi phthemab,
Google’s inability to crawl your website is not related to the AgeVerify plugin. Our plugin does not change any links or content on your website, and the overlay (age verification prompt) only happens when the rest of your content is loaded.
Further, AgeVerify is written with JavaScript which is ignored by search engine crawlers.
A 404 error (which is a page not found error) would suggest that either the wrong page was registered in the Google Webmaster tools, your sitemap.xml file has incorrect data, or you have links on your website that are pointed to non-existent pages.
Hope that helps.
[ Signature deleted ]