Chrome doesn't send “If-Modified-Since”

Question

I want browsers to always add (except first time) \"If-Modified-Since\" request header to avoid unnecessary traffic.

Response headers are:

Accept-Ranges:         


        

Answer 1

I've been chasing this issue for some time, thought I'd share what I found.

"The rule is actually quite simple: any error with the certificate means the page will not be cached."

https://code.google.com/p/chromium/issues/detail?id=110649

If you are using a self-signed certificate, even if you tell Chrome to add an exception for it so that the page loads, no resources from that page will be cached, and subsequent requests will not have an If-Modified-Since header.