Runtime: Cancelled Network Requests

Overview

With regards to requests in the Network tab with the status "cancelled" - there is no default timeout on AJAX requests in Chrome/Chromium, however there are a few places where Chrome/Chromium will cancel a request:

• the DOM element that caused the request to be made got deleted (i.e. an IMG is being loaded, but before the load happened, the IMG node was deleted)

• something was done that made loading the data unnecessary. (i.e. started loading a iframe, then changed the src or overwrote the contents)

• there are lots of requests going to the same server, and a network problem on earlier requests showed that subsequent requests weren't going to work (DNS lookup error, earlier (same) request resulted e.g. HTTP 400 error code, etc)

• this might also happen if you have a button that submit's the request wrapped in a form element, if preventDefault isn't called on the click event two request will be sent and result in the cancellation.

Resources: 

net-internals