A 404 error means that when a search engine attempted to display a page nothing was returned by the server. Sites can encounter 404 errors in a variety of ways. A page that used to exist was removed but it is still listed in the Sitemap, one of the webpages on the site links to the removed page, or there is a typo in the link that points it to a page that has never existed before.
Google does not like links or embedded content that produces 404 errors or otherwise can’t be accessed by the crawler.Most search engines assume a 404 error means the page is either outdated or not updated properly, and are signals to Google that the site might not be the highest quality.You should try to avoid having content that leads to a dead or unresponsive page.
If you have embedded content, all of that content should be live and readable by search engines.