Cloudflare Always Online™ limitations:
- Always Online™ cache is built from Cloudflare’s Always Online™ crawler. It crawls Free customers once every 7 days, Plus and Pro customers once every 3 days, with Premium customers crawled daily. Note: The crawler does not obey robots.txt.
- Only content hosted on the domain that has Always Online™ enabled will be cached in the Always Online™ cache.
- Cloudflare doesn’t cache every page on your site. A limited cache of your site will be displayed, generally 1-3 pages, which means that only some pages on your site will be viewable if your server goes down.
- Recently added sites won’t have a large cache of pages available, which means that Always Online™ may not work if you very recently added the site.
- Cloudflare won’t be able to show private content or handle form submission (POST, SSL) if your server is down. An error will be displayed on checkout pages or pages requiring a login to view.
- In order to trigger Always Online™, your web server must be returning a standard HTTP timeout Error code of 502 or 504. Always Online™ will also work when it encounters issues contacting your server (Cloudflare Errors 521 & 523), timeouts (522 & 524), SSL errors (525 & 526) or an unknown error (520). Always Online™ will not be triggered for other HTTP response codes, such as 500, 503, database connection errors, internal server errors, or empty replies from the server.
- If you are on a paid Cloudflare plan, we recommend customizing the Cloudflare error pages that may be displayed when Always Online™ is triggered.
- If your site has a database error (database connection or otherwise) Always Online™ will not be triggered, as your web server is likely still available even if there are database issues.
- Having caching headers coming from your server in the response (Cache-Control, Expires, etc.) that tell us not to cache the resource will cancel out most of Cloudflare’s caching ability and Always Online™.
- If you have the United States listed as a country on your Threat Control block list, the Always Online™ crawler will not be able to crawl your site.
- A “Cache Everything” page rule is enabled with the “Edge Cache Expire TTL” lower than the caching frequency (Free customers: 7 days, Pro customers: 3 days, and Business and Enterprise customers: 1 day). In this cache, the Edge Cache Expire TTL will cause the Always Online™ cache to be purged in the corresponding interval.