What it means
Something broke while generating the response: an application error, a failed database query, exhausted memory, a broken plugin. The browser or crawler did nothing wrong — the page simply failed to render.
SEO impact
- Persistent 500s remove URLs from the index: search engines retry a few times, then drop the page.
- Intermittent 500s are worse for diagnosis — crawls sample the site, see random failures, and crawl budget is spent on retries.
- 500s on template-critical URLs (category pages, pagination) can break the discovery of everything beneath them.
Finding them
Log files are the source of truth: count 5xx responses by URL and by time window to separate constant failures from load spikes. A crawl catches a snapshot; server logs catch the pattern. Crawl again during traffic peaks if the errors are intermittent.
SpiderHead marks every 5xx in a crawl and correlates them with inlinks, so you can see how much of the site hangs behind a failing template.
FAQ
Do search engines deindex pages with 500 errors?
Yes, if the errors persist. Crawlers retry temporarily failing URLs for a while, but sustained 500s lead to removal from the index.
What is the difference between 500 and 502?
500 means the origin server itself failed while processing the request. 502 means a gateway or proxy received an invalid response from the origin — the failure happened one hop further back.