What does this report contain?
URLs that return any 5xx Server Error HTTP status code, such as a 503, often caused by a temporary server performance problem or a permanent issue.
How can this report be used?
If the errors cannot be replicated, it suggests a temporary server performance issue, which may have been caused by the crawl. If the issues can be replicated, the links to the 5xx URLs may be incorrect or the script which generates the pages may be broken.