Google Chrome ends Manifest V2 support, closing uBlock Origin workarounds

Google Chrome has entered the final stage of its migration away from Manifest V2 (MV2), the extension platform that still powers uBlock Origin and a number of other add-ons. According to a discussion in the W3C WebExtensions Community Group repository, the Chromium feature flag kExtensionManifestV2Disabled, which allowed controlled disabling of MV2 extensions, has now been removed entirely.

Chromium contributor Andrey Bershanskiy compiled the recent changes, and Google engineer Devlin Cronin explained the reasoning in a code review comment: the flag had been enabled by default for over a year, so the feature and its "effectively dead code" were deleted, along with tests that depended on the earlier warning phase.

Why Google is dropping MV2 for good

Cronin said MV2 extensions are no longer permitted in any supported version of Chrome. "We won't be able to provide and maintain this functionality indefinitely due to the complexity and tech debt, as well as the security risks it entails — we've actually found a number of bugs that are specific to MV2 lately," he wrote. Google will not hide the change behind a compilation flag, though the MV2 code will not be stripped out in one step: "many of these things will continue working for awhile (but they will go away eventually, and some may go away sooner than others)."

The escape hatches are closing

The workarounds that kept MV2 add-ons running are going away together with the flags. Chromium 150 lost the ExtensionManifestV2Disabled option; Chromium 151 is expected to lose ExtensionManifestV2Unsupported, ExtensionManifestV2Availability and, in all likelihood, AllowLegacyMV2Extensions. The Windows Registry modification that extended MV2 availability on Chrome and Edge is set to stop working after Chromium 151.

Edge, Opera, Brave and Firefox

Other Chromium browsers are following the same path at different speeds. Microsoft Edge began switching off uBlock Origin in February. Opera had committed in October 2024 to supporting MV2 for longer, but uBlock Origin developer Raymond Hill said he received a message from Opera stating that it planned to abandon MV2-based extensions, adding that a submission of version 1.70.0 had gone unreviewed for weeks. Opera says its position is unchanged and that MV2 extensions remain usable for now, while confirming that new MV2 uploads will no longer be accepted to its store and that less-used MV2 extensions will stop being downloadable. Brave has said it will keep MV2 support, and Mozilla Firefox supports both MV2 and MV3.

For users who stay on Chrome, the recommended path is uBlock Origin Lite, which is built on MV3 — although its filtering is less thorough than the original. The change closes an era of content blocking on the world's most widely used browser.