In this article, you can find details about the error codes for failed optimizations and what to do about them.
You can find the specific error code by hovering over the "Skipped" text.
Skipped 2000: Optimization was skipped because X-Nitro-Header: Disabled was detected
This means that at the time of the optimization attempt, one of the following was true:
The service was in Test Mode.
The page was excluded from optimization via the Excluded URLs setting or from the “Select what post/page types get optimized” setting in the NitroPack plugin.
The Included URLs setting is active, allowing NitroPack to optimize only the list of included URLs and the skipped URL is not part of the list.
NitroPack does not optimize the page type by default (e.g., checkout, cart and user profile pages).
Make sure to perform an individual purge of the URL after fixing the issue. The page should be optimized soon after that.
Skipped 2006: Optimization has been skipped due to a third party caching system detected
You may encounter this error if you’re using another caching plugin. In that case, please turn off all other caching plugins listed in this article.
This error could also be caused by a lack of integration with Cloudflare, Sucuri, or a Reverse Proxy. Follow the instructions in the linked articles if you’re using one of these services.
Redirected 301/302: URL is permanently/temporarily redirected to another URL
Check if the URL in question actually redirects to another one. If it does, remove it from the sitemap, if you’ve submitted one in the Cache Warmup panel;
Also, please make sure that the sitemap is up to date with any changes you’ve made.
Forbidden 403: Your server did not allow us to optimize the page
You need to allowlist NitroPack’s IPs (found in this article) in your hosting, Sucuri, Wordfence and any other active security tool/plugin. After that, perform an individual or full cache purge.
Another cause for this error could be Cloudflare’s Super Bot Fight Mode. We’re in contact with Cloudflare to resolve the issue, but in the meantime, you will have to disable this feature.
404: Not Found
This error means that the page was not found. This can indicate the presence of dead links somewhere on the site or the sitemap. Please make sure that all links on your site/sitemap are up to date.
When a URL returns a 404 Not Found error, NitroPack cannot optimize it.
5000: Unknown
This is an unexpected internal issue and may be fixed by purging the cache for the page.
If the issue persists after purging the cache, please contact our support team at [email protected].
5002: Reading response timed out
NitroPack attempted to reach your origin server but wasn’t able to and timed out. You can try manually purging the pages with this error, so NitroPack can attempt to reach them again.
Also, please check in with your hosting as this is very similar to a 502 Bad Gateway Error.
5005: Skipped
The error means that Critical CSS extraction failed for the page.
A quick workaround is to perform an individual purge for the page until it’s optimized.
In case a large number of pages are affected by this issue, please contact [email protected].
5010: Skipped
The error means that removing unused CSS failed for the page.
A quick workaround is to perform an individual purge for the page until it’s optimized.
In case a large number of pages are affected by this issue, please contact [email protected].
5009: Not an HTML page
This error appears when the system receives an optimization request for an URL that doesn’t point to a web page. For example, a URL that points to a CSS file directly.
5011: The page source file is too big
The page's HTML file has to be under 5MB for NitroPack to optimize it. This does not include external resources like CSS, JavaScript and images.