Errors / issues while using RocketCDN

No images loaded on SiteGround hosting

SiteGround implemented an Antibot AI captcha system on websites using Siteground for WordPress hosting:

Please ask their support to either allow your RocketCDN CNAME or to disable this  Antibot AI captcha.

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 RocketCDN servers IPs are probably blocked by your server, a firewall, or a security plugin. Please allow these IPs on all these security levels.

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 403 when RocketCDN is active

Error 403 (forbidden) indicates that RocketCDN does not have permission to take the assets from the origin server and/or serve them on your domain.

Such issue is quite common and is caused by any kind of security plugin, firewall setting, and/or by hosting if there is any such mechanism active (especially if you use Shared hosting account type).

So first, try to deactivate your security plugin if you use one. If it solves your issue, contact the support of this plugin to know how to allow RocketCDN to take the assets from origin server and serve them on your domain.

If it’s not enough, you will have to contact your hosting provider to help you with this issue.

Errors 404 on your assets

If you get a 404 on a file served from 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 502 and 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 the time, 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 error 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)

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.

☝️ If you notice that some files, served from RocketCDN, are pointed out by PageSpeed Insights’ diagnostics or opportunities, it doesn’t mean that the issue is with RocketCDN but rather with the files it-selves. In most cases, 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.

Excluding files by extensions in RocketCDN

If you're having issues with serving certain types of files from RocketCDN, you can exclude them like this:

  • JavaScript files: /(.*).js
  • CSS files: /(.*).css
  • Images: /(.*).jpg , /(.*).png, /(.*).webp or /(.*).svg

RocketCDN subscription modal box keeps opening

This usually indicates that your WordPress admin is cached by a server cache layer. Please clear this cache and exclude your WordPress admin from being cached.

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