304: Not modified and front end caching

Question

I am using a PHP script to serve files. I would like to be able to send back a 304 not modified header in my http response if the file has not changed since th

Answer 1

I had this problem and it turned out to simply be that I had Firebug open. This has an option under the Net tab "Disable Browser Cache" that is ticked by default. There is a similar option in Chrome's developer tools, one of the tick boxes on the bar under the menu bar.

Unticking these options resulted in the browser correctly sending HTTP_IF_MODIFIED_SINCE and everything working fine after all (even with Firebug or Chrome Dev Tools open).