Why browser does not send “If-None-Match” header?

Question

I\'m trying to download (and hopefully cache) a dynamically loaded image in PHP. Here are the headers sent and received:

Request:

GET /url:resource/P         


        

Answer 1

This happened to me due to 2 reasons:

1. My server didn't send etag response header. I updated my jetty web.xml to return etag by adding the following:

   
       etags
       true
   
   

2. The URL I called was for xml file. When I changed it to html file, chrome started sending "if-none-match" header!

I hope it helps someone