Troubleshooting RocketCDN

In this article

RocketCDN: a pull CDN

This means that the assets are pulled from the origin server to the RocketCDN network. 

In RocketCDN the assets won't be pushed to the network, and it won’t take any given time before they are cached in all the CDN network servers.

Here are a few notes on how the pulling process goes: 

  • The assets need to be requested before getting cached in each RocketCDN network server. 
  • If an asset is not cached in a given RocketCDN server by the time it was requested, then the request will be taken to the origin server to pull the asset.

In this case, the first network visitor will experience a slightly slower response only for that first time:

  • Subsequent requests to that RocketCDN server will receive the previously cached asset, and the expected faster response. 
  • After a 120-days TTL (a RocketCDN standard) the assets cache will be automatically cleared from the RocketCDN cache, and they will need to be cached in the servers again, the same way as described above.

✅ Basic requirements for RocketCDN to work:

  1. As RocketCDN is a pull CDN, your site must be publicly accessible for the assets to be pulled from your server, that means it won't work for locally hosted sites or sites blocked from the public by htaccess authentication, "maintenance mode" plugins or similar. 
  2. The following IP has to be allowlisted by your server, firewall, or security plugin to be able to subscribe :
  3. All StackPath previous CDN subscriptions for your domain must be deleted.

❌ Error notices during the subscription process

• RocketCDN is not available at the moment. Please retry later

If you see this message where you should be able to subscribe to RocketCDN, this means that your site can’t communicate with RocketCDN server. The IP is probably blocked by your server, a firewall, or a security plugin. Please allow this IP on all these security levels.

• A CDN site with domain already exists

RocketCDN relies on StackPath CDN and maybe a previous StackPath CDN subscription still exists. Please contact StackPath support to delete it.

If there’s no StackPath CDN subscription at all, please contact our support.

⁉️ Errors / issues while using RocketCDN

☝️ If you notice that some files, served from RocketCDN, are pointed out by PageSpeed Insights’ diagnostics or opportunities, it doesn’t means that the issue is with RocketCDN but rather with the files it-selves. In most of case, you’ll get the same diagnostics or opportunities if the files are served from your domain. In any case, the purpose of RocketCDN is to serve faster your static files - JS, CSS, images - to your visitors from servers close to their location, but not to improve your PageSpeed Insights score.

• RocketCDN cache purge failed: The API returned an unexpected response code.

It means the response from the API was not considered successful (we expect a 200), so possibly there were some issues on the API side when doing the request or maybe your server is blocking the request, please check with your server / hosting provider. This is often a temporary issue. Try a bit later.

• Errors 404 on your assets

If you get a 404 on a file served form your RocketCDN CNAME (, this means that this file is also in 404 on your origin domain. Fix this 404 on your site and RocketCDN will be able to serve it right after.

• Errors 504 on your assets

The RocketCDN server, when acting as a proxy did not receive a timely response from the origin server, so it can’t serve your asset.

Imagine the request as a phone call, but it never even rings. It just says 'please try your call again later', that’s what happens there.

Most of times, it’s because your server doesn’t allow RocketCDN to pull your assets. In that case you’ll have to ask your host support to allow all RocketCDN IPs, you’ll find them all here.

More details here: Troubleshooting 502 and 504 Errors

• Cross-Origin Resource Sharing (CORS) errors in the console

If you get this kind of CORS errors in the browser console after activating RocketCDN:

Access to font at '' from origin '' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

Cross-Origin Resource Sharing (CORS) is an HTTP-header based mechanism that allows a server to indicate any other origins (domain, scheme, or port) than its own from which a browser should permit loading of resources.

An example of a cross-origin request: the front-end JavaScript code served from uses XMLHttpRequest to make a request for

When you find this error in your browser console it means the correct CORS rules are not in place. WP Rocket enables them by default on sites that use an htaccess file, but if you use an NGINX server you will have to add the following in your virtual host file:

location ~* \.(eot|css|otf|ttf|woff)$ {  add_header Access-Control-Allow-Origin *;  }

More info: Resolving issues with CDN and fonts (icons)

• No Subscription

Please follow the steps provided in this article: No subscription: How to (re)activate RocketCDN on my site

• RocketCDN stopped working after a migration

First of all, be sure to follow thoroughly the guide provided here: Changing Domains and Migrating Sites with WP Rocket.

Then for your RocketCDN subscription, although we are working on improving this, at the moment the step will need to be done manually by us because your RocketCDN CNAME is specifically linked to one domain, so let us know when you’ll need to migrate it.

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