Everything is reloaded on cached view even though it's expires are set

Web Performance Discuss Test Results
1

I’ve been wondering if this results is a WPT bug or a wrong code on my part:

http://www.webpagetest.org/result/151215_ZZ_8GM/

The Cache Static Content is rated at: A

and all static object’s max-age is also set. But on the cached view, every images is reloaded:

http://www.webpagetest.org/result/151215_ZZ_8GM/1/details/cached/

How could this happen?

2

I don’t think it’s a measurement bug. The “bytes in” (overall) measures at the socket level and is guaranteed to be the number of bytes that came in over the wire (even if there was a problem with reporting individual requests). I also tried a few other HTTPS sites and they appear to be reporting correctly (was a bit worried because I just updated the HTTPS reporting flow for Chrome this morning).

I think you’re tripping over a Chrome bug (or edge case) because Firefox appears to be correctly serving things from cache. I haven’t had time to dig in and see which headers may be triggering it though.