Chrome doesn't send "If-Modified-Since"

http if-modified-since
GarryIV picture GarryIV · Apr 6, 2012 · Viewed 9.1k times · Source

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

Response headers are:

Accept-Ranges:bytes
Cache-Control:max-age=0, must-revalidate
Connection:Keep-Alive
Content-Length:2683
Content-Type:text/html; charset=UTF-8
Date:Thu, 05 Apr 2012 13:06:19 GMT
Keep-Alive:timeout=15, max=497
Last-Modified:Thu, 05 Apr 2012 13:05:11 GMT
Server:Apache/2.2.21 (Red Hat)

FF 11 and IE 9 both send "If-Modified-Since" and get 304 in response but Chrome 18 doesn't and get 200.

Why? How to force Chrome to sent "If-Modified-Since" header? I do not know if it important or not but all requests going through HTTPS.

Answer

Neek picture Neek · Jul 18, 2013

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.

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