Why is Lighthouse failing my cached files?
I'm using Google Lighthouse to calculate a performance score. One of the criteria is caching static assets such as images and scripts.
I don't have control over all of these, but the ones I do have control over the cache has been set to 30 days. However, Lighthouse is still reporting these as an issue. Lighthouse does report these as having a 30d cache, but still reports as an issue.
What do I need to do to rectify this?
Please see screenshot below:
Lighthouse will warn you to serve static assets with an efficient cache policy if your score for that audit is not greater than or equal to 90. It will also list all of your static assets in the details summary (regardless of whether they pass or not).
Since you do not have control over some of your static assets, your score appears to be lower than 90, and therefore, you are still seeing your static assets that pass the audit in the details summary.
You can verify this by saving your results as a JSON file, opening it in any text editor, and searching for the section containing "uses-long-cache-ttl".
The score underneath will likely be less than 90.
You can learn more about this particular audit by visiting this link:
https://developers.google.com/web/tools/lighthouse/audits/cache-policy