ETag header missing on resources: what it is, why it matters, and how to fix it

Static resources are served without an ETag HTTP header. ETags enable conditional requests that allow browsers to validate cached resources without re-downloading them.

Without ETags, browsers cannot efficiently validate whether cached resources have changed. They must either re-download the full resource or rely solely on Cache-Control expiration. ETags enable 304 Not Modified responses that confirm cache validity with minimal bandwidth, improving performance for returning visitors.

Ensure your server generates ETag headers for static resources. Most web servers enable ETags by default. If they were disabled, re-enable them in your server configuration.

This is a low-severity issue: a polish item. Fix it in batches during scheduled maintenance; the win is cumulative quality, not a step change. It belongs to the performance family of checks.

Run a free Dr Urls audit: it crawls your site, detects etag header missing on resources on every affected page, shows example URLs, and generates a ready-to-use fix task. Re-scan after fixing to verify the issue is gone.