This section identifies pages that return a 5xx server error code.
A server returns a 5xx error code when it encounters an error or is unable to fulfill a request. 5xx errors can be caused by many reasons, but the most common include the request timing out, the requested page being inaccessible, or the site being busy. As a result, the crawler was unable to access the requested page.
5xx errors mean that search engines are unable to access, crawl and index a page. These error codes are also bad for user experience, another problem for SEO.