On Monday, June 3, 2024, some people using Beta, Dev, and Canary builds of Google’s Chrome browser will be presented with a warning banner when they open their Manage Extensions page—located at chrome://extensions.
The banner will say Manifest V2 legacy browser extensions will stop working soon. These extensions include ad blockers and other content filters that rely on the Manifest V2 API. And while the leading ad blocking extensions more or less support Manifest V2’s successor, conveniently named Manifest V3, there’s still some argument that these filters will be at a disadvantage under version 3 when they’re no longer allowed to use version 2.
In any case, users will be warned that V2 is about to be released.
“This will be followed gradually over the coming months by the disabling of these extensions,” said David Lee, product manager for Chrome Extensions, in a blog post published Thursday.
“Users will be directed to the Chrome Web Store where they will be recommended alternatives to Manifest V3 for their disabled extension. For a short time after extensions are disabled, users will still be able to re-enable their Manifest V2 extensions, but over time, this toggle will also disappear.”
A browser extension’s manifest file is where developers declare its capabilities through the Chrome Extension API.
The transition from Manifest V2 to Manifest V3 has been underway for at least five years. It makes new APIs available to browser extensions and removes old ones. The most notable of these is the blocking version of the webRequest An API that is used to intercept and modify network traffic before rendering. Under Manifest V2, this is what extension developers use to stop ads, trackers, and other content from appearing on pages and to prevent certain scripts from running.
The new MV3 architecture reflects Google’s open desire to make browser extensions more performant, private and secure. But the Internet giant’s attempt to do so has been bitterly contested by creators of privacy protection and content blocking extensions, who argue that Chocolate Factory’s new software architecture will lead to less effective privacy extensions and content filtering.
As a result of this years-long battle and concessions that Google made to frustrated extension developers, the current version of MV3 is generally perceived as better than what was originally proposed, but did not fully address developers’ concerns or provide functionality that was equivalent to , which is suggested removed.
Li acknowledged the problem, noting the ways in which Google has responded by adding support for user scripts, for off-screen documents that access the DOM API, and by increasing the number of rule sets in declarativeNetRequest API (replacing the webRequest) up to 330,000 static rules and 30,000 dynamic rules. These policies can be used by ad blockers to remove ads and other things for users.
Manifest V3 is already supported to varying degrees by other browsers, such as Edge, Firefox, and Safari. And until early 2025, when API changes are available for a while in Chrome’s stable channel, Manifest V2 extensions will stop working.
Enterprises using the ExtensionManifestV2Availability policy will be spared until June 2025.
According to Li, more than 85 percent of actively supported extensions in the Chrome Web Store support Manifest V3, “and the best content filtering extensions have versions of Manifest V3 available—with options for users of AdBlock, Adblock Plus, uBlock Origin, and AdGuard . “
For users of uBlock Origin, which runs on Manifest V2, “options” means using the less capable uBlock Origin Lite, which supports Manifest V3. ®
