Chrome's June update removes the only switch for running the browser's old extension standard, ending a workaround that kept the full version of the popular open source ad blocker alive in the default browser.
Chrome 150 ships later this month, and with it goes the last switch that let users keep pre-2024 ad blockers running inside the world's default browser. The change is a quiet Chromium commit — CL 7813942 on Gerrit — that drops a flag called kExtensionManifestV2Disabled, the residual loophole that allowed power users to keep Manifest V2 extensions installed even after Google stopped supporting that older extension standard. It does not end ad blocking in Chrome. It ends a specific workaround that a subset of power users relied on to run the full version of uBlock Origin, AdGuard's older MV2 builds, and other extensions that never made the jump to the new system.
The change is small in code, large in effect. A Googler commenting on the commit put it this way: "MV2 extensions are no longer allowed in any supported version of Chrome, and we are removing support for them and the associated functionality. We won't be able to provide / 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). Of course, other browsers can continue supporting these if they so desire." The flag was a leftover escape hatch for users who force-enabled it through Chrome's experimental settings. With it gone, anyone whose ad blocker depends on Manifest V2 will see it stop loading after upgrading. The framing in some coverage, including the Slashdot summary of the original 9to5Google report, called this the "end of popular ad blockers." That overstates the case. MV3-based blockers, including uBlock Origin Lite and AdGuard's MV3 release, continue to work normally in Chrome 150.
What users actually lose is access to the feature set that Manifest V2 allowed and the new MV3 system constrains. The original uBlock Origin supports advanced filtering modes, custom dynamic filter rules, and granular per-site controls that the MV3 "Lite" build deliberately simplifies to fit Chrome's newer security model. Power users running complex custom filter lists, advanced blocking modes, or extensions that never shipped an MV3 version lose a real option inside Chrome. Everyone else, including the vast majority of users running the Lite build or no blocker at all, sees no functional change.
The security argument Chrome's engineers give on the commit is plausible. Maintaining a dead-code bypass for an unsupported extension standard creates attack surface, and the commit comment notes that active bugs were found in the flag's code path. The honest reading is that the flag's removal is overdue housekeeping, not a policy event aimed at ad blockers. The harder question is who decides what runs in the browser most of the world uses. Chrome's extension rules govern Edge, Opera, and the Chromium underpinnings of Brave, Vivaldi, and ungoogled-chromium. A flag removed at the Chromium level disappears from every browser built on it, unless that browser's maintainers patch their own build to keep the option alive. Brave and Vivaldi have, in past Chrome rule changes, chosen to preserve user-visible settings that Google drops. Whether they do so for this one is a watch item.
The user-side options, for people who want the old extension model back, are concrete. Firefox still supports Manifest V2 in full, including the original uBlock Origin with its advanced feature set. uBlock Origin Lite works in Chrome 150 for users who only need standard ad blocking. Chromium-based browsers that maintain their own patches can technically keep the flag, though that requires a willing maintainer and a user willing to trust a non-Google build. For the small population whose workflow depended on a specific MV2-only extension with no MV3 equivalent, the practical move is Firefox, or waiting to see which fork patches the flag back in.
Chrome's stable channel is currently scheduled to reach version 150 later this month, with the residual Manifest V2 code paths slated for full removal in version 151. After that, the only path back to the old extension model runs through a non-Chrome browser.