Bug 193533 – Preloaded content is always retrieved from cache

• Component: Page Loading
• Status: NEW

[Oliver Joseph Ash]

Created attachment 359368 [details]
Reproducer

If a request is preloaded, Safari will always retrieve it from the cache, regardless of the cache headers for that request.

Attached an example.

This is the same as https://bugs.webkit.org/show_bug.cgi?id=187726, but more general in scope—the bug is not specific to the "Disable Cache" feature in the web inspector.

[Oliver Joseph Ash]

Created attachment 359369 [details]
Screenshot

[Radar WebKit Bug Importer]

<rdar://problem/47352078>

[Oliver Joseph Ash]

Created attachment 359462 [details]
Reproducer 2

I've improved the test case and included steps to reproduce in the README.md.

[Sergio Mattei]

This is a huge blocker for web development on Safari. 

This bug completely breaks the NextJS dev cycle. Are there any updates on this? It's very odd to enable "Disable Caches" and the browser to completely ignore my setting.

[Hannes Ljungberg]

Encountered this issue today with Safari (Version 18.0 (19619.1.26.111.10, 19619)). 

Usage:

<link
  rel="preload"
  href="https://example.com/foo"
  as="fetch"
  crossorigin="anonymous"
/>

Server responds with:

Cache-Control: no-cache
Etag: barbaz

Now, when reloading I would expect Safari to send a HTTP request with "If-None-Match:  barbaz" but instead it caches the response indefinitely(?) and serves it from "Memory Cache" with no HTTP requests hitting the server. Both Firefox (130.0.1) and Chrome (129.0.6668.70) behaves as expected.

My use-case requires all cached preloaded requests to be revalidated with a "If-None-Match" before usage and since Safari ignores the directive to revalidate I have to opt-out of using this optimisation altogether.