With Always Online, there are certain limitations which are outlined below:
Always Online cache is built from Cloudflare’s Always Online crawler. We crawl Free customers once every 7 days, Pro customers once every 3 days, and Business and Enterprise customers 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. Specifically, Always Online will cache the first 10 links from your root HTML, then just the first links from each of those pages, and finally the first links from each of those subsequent pages. This means that only some pages on your site will be viewable when your origin server goes down.
Recently added sites won’t have a large cache of their site available, which means that Always Online may not work if you only added the site a few days ago.
Cloudflare won’t be able to show private content or handle form submission (POSTs) if your server is down. Visitors will be shown an error on things like checkout pages or items requiring a login to view.
In order to trigger Always Online, your web server will need to be returning a standard HTTP Error code of 502 or 504 timeout. Always Online will also work when we encounter issues contacting your origin (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 404s, 500, 503, database connection errors, internal server error, or empty replies from server.
If you are on a paid Cloudflare plan, we would strongly recommend customizing the Cloudflare error pages that may display if 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 the the database is having issues.
You have caching headers coming from your server in the response (Cache-Control, Expires, etc.) that tell us not to cache the resource. This will cancel out most of Cloudflare’s caching ability and Always Online.
You have the United States listed as a country on your Threat Control block list. If the US is listed as a block, 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.