Regressed Predictive prefetch makes duplicate HTTP requests in iframes, causing false ad impressions

Published: | Categories: Networking


Online advertising network companies have reported to Mozilla that they are observing a lot of duplicate impressions coming from Firefox 52 users. This issue has turned out to be a bug in the newly enabled network predictor prefetch service, making repeated GET requests even to the URL of scripts or images dynamically inserted inside inline frames.

The predictive prefetch feature will be disabled in Firefox 52 soon remotely, and re-enabled in Firefox 55 once the issue is examined and solved.