Created by Wang, Jerry on Oct 15, 2015

If you are careful, you will notice that in the Network panel of the new developer tool, some request headers are followed by the following text:

The screenshot shows a request to visit www.imququ.com. Since the blog is HTTPS and HSTS enabled, the browser will automatically replace HTTP with HTTPS in the address to send within the max-age specified by HSTS. That is, the first HTTP request was not actually made at all, and the corresponding request header certainly should not exist. But Chrome 32 will also display partial request headers for such requests, with a CAUTION:Provisional Headers are shown. In general, if you see this prompt, the request was not sent. In addition to the above, the request may be blocked by some extension such as Adblock. Requests from local cache or dataURL will also be displayed this way.