Knowledge base v2.13.0 · Community edition · data through 2 October 2026
Thing · Status code
The HTTP status code for a temporarily unavailable server, the right answer for planned maintenance and short outages.
Documented in
Google's Search Central post on CDNs says that if Google cannot recognise an error message served with a 200 status as an error, all pages showing the same message may be dropped from the index as duplicates, and recovery can be slow because Google has little incentive to recrawl duplicates. For bot-verification interstitials it recommends sending crawlers a 503 status.
Search Central blog (24 December 2024) · Day 2 · Handling web duplication
Google's crawl rate guide says that when a significant number of URLs return 500, 503 or 429, Google reduces the site's crawl rate, which starts increasing again automatically once the errors drop; it warns against doing this for longer than 1-2 days.
Google · Day 3 · How long does it take to..?
Slide and stage claims that name it, the ones Google’s documentation does not cover first.
A rise in HTTP errors in crawl reports can come from a CDN throttling crawlers by injecting 429 or 503 responses on the network path between Google's crawler and the site.
Gary Illyes · Day 1 · How crawling errors affect Search
For temporary blocks return 503 or 429, never a 200 page with a captcha or error message, which becomes a soft 404 and can replace real content in the index. Verify Googlebot by reverse DNS, not by user agent.
Ibrahim Anjro · Day 1 · How crawling errors affect Search
Do not answer verified Googlebot with 401, 402 or 403, for example from a login wall, a paywall or a pay-per-crawl setup: Google treats them like 404 and drops the pages, and Google's status code page says not to use 401 or 403 to limit crawling; to slow crawling temporarily, return 429 or 503.
Ibrahim Anjro · Day 1 · How crawling errors affect Search
Return real error status codes for error states, 404 or 410 for missing content and 503 for outages such as a failed database connection, also in single-page apps; a 200 page whose main content is only an error message is treated as a soft 404 even when header and navigation look normal.
Ibrahim Anjro · Day 2 · Understanding what's on a page
Check what your CDN or bot protection serves to verified Googlebot and to the AI agents you want to allow; if crawlers must get a challenge page, return it with a 503 status as Google recommends, never as a 200 page across many URLs, which Google may cluster as duplicates.
Ibrahim Anjro · Day 2 · Handling web duplication
Kit items about 503: their own words name it, or several of the claims they rest on do.
Never serve bot challenges or error pages to crawlers with a 200 status
Rests on 7 claims, 4 of them naming 503
Answer planned maintenance and short outages with 503, for a day or two at most
Rests on 11 claims, 3 of them naming 503; its own words name 503
Never serve error states, empty results or failed data loads with a 200 status
Rests on 10 claims, 2 of them naming 503
Things named in the same claim, with the number of claims they share.