Chrome’s “Manifest V3” plan to limit ad blocker extensions has been delayed

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For several years, Google has wanted to phase out Chrome’s current extensions system in favor of a more restricted one, creating more restrictions on filtering extensions that block ads and/or help protect user privacy. The new extension system called Manifest V3 technically reached the stable channel in January 2021, but Chrome still supports the older, more powerful Manifest V2 system. The first steps towards the Manifest V2 shutdown were supposed to begin in January 2023, but as 9to5Google first noted, Google now says it has delayed the mandatory move to Manifest V3 and won’t even have a new schedule ready for the V2 shutdown by March .

The old timeline started in January 2023 when beta versions of Chrome started running “experiments” that disable Manifest V2. This would move to the stable release in June, with the Chrome Web Store manifest banning V2 extensions in January 2024. The new timeline is that there is no timeline and each step is now listed as “postponed” or “under review”.

In a post about the delay, Chrome Extensions Developer Advocate Simeon Vincent says, “We heard your feedback on common challenges arising from the migration, specifically the inability of the service worker to leverage DOM features and the current hard limit on lifetime by Extension Service staff. We’re mitigating the former with the Offscreen Documents API (added in Chrome 109) and are actively looking for a fix for the latter.” After adding that every step of the timeline is on hold, Vincent said, “Expect to see more by March 2023 about to learn the updated phase-out plan and schedule.”

Google’s statement only addresses the second controversial change to Manifest V3: turning off an extension’s ability to launch a hidden background page due to background processing. Google wants all background processing to be done by service workers, but that’s a complicated environment compared to normal web development and brings with it many more limitations. Google’s delay is all about fixing some of those background restrictions.

The new Manifest V3 timeline just saying everything is delayed.
Enlarge / The new Manifest V3 timeline just saying everything is delayed.

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Google’s post doesn’t mention filtering add-ons, so it doesn’t sound like the world’s largest advertising company is making a change of heart when it comes to ad blockers. The big problem for these extensions is to destroy the “WebRequest API” that allows ad blockers and other filtering tools to modify Chrome’s network requests on the fly. Usually this is used to create huge lists of websites (ad servers) that the extensions want to block access to. Google threw a bone to these extensions by creating a new API that allows a limited list of URL blocks, but this is only a static list of 30,000 URLs, while a typical installation of uBlock Origin comes with 300,000 dynamic filtering rules. Some ad blockers will try to play with the Manifest V3 version within these rules, but Google will undermine their effectiveness and does not want to implement any of the sensible solutions that would allow them to work at the current level.

“Fraudulent and menacing”

Google started this mess in 2018 with a blog post outlining a plan for “default-trusted Chrome extensions.” As part of the launch of Manifest V3, Google’s official story is that it wanted to restrict “too broad access” to extensions and that a more restricted extension platform would allow for “more powerful” extensions. The fun side effect of all this is more limited ad blocking, which would handily help Google’s bottom line. The old timeline would have at last implemented the full transition to Manifest V3 six years after that first blog post, but now it sounds like it will take even longer.

The Electronic Frontier Foundation doesn’t buy Google’s selling point, calling Manifest V3 “fraudulent and threatening” about a year ago. The EFF said that Manifest V3 will “limit the abilities of web extensions – particularly those designed to monitor, modify and charge for aside the conversation your browser is having with the websites you visit.” The privacy group said it’s “doubtful Mv3 will do much for security” as it only restricts website content filtering and doesn’t collect, so malicious extensions could still suck out all your data. The EFF also says performance isn’t a valid excuse, citing a study showing that downloading and rendering ads hurts browser performance. If Google is concerned about security, it could monitor extended storage better.

The Chrome team seems to have committed to a heel turn lately. The company also refused to block tracking cookies until it can build a tracking and advertising system into Chrome for the first time (this has also been repeatedly delayed). If people are fed up with Chrome’s anti-user changes propping up Google’s business model, there are alternatives. Some Chromium-based forks like Brave and Vivaldi have committed to keeping Manifest V2 running if Google shuts it down. Of course, there’s always Firefox, which says it will move to Manifest V3 along with Google, but will add back the WebRequest API that filter add-ons rely on.

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