Google closes final Chrome loophole for old ad blockers

Google plans to end the last Chrome workaround for Manifest V2 extensions in Chrome 150 and 151, according to reports from 9to5Google and The Verge. The change cuts off users who kept older ad blockers such as uBlock Origin running after Google began the Manifest V3 migration.

Google started this fight years ago when its Chrome team pushed extension developers from Manifest V2 to Manifest V3. The company says the newer system gives users more privacy and security. Ad blocker developers have argued that Google’s design limits the blocking methods that made tools such as uBlock Origin powerful.

The June change targets the ExtensionManifestV2Disabled flag. Power users used that setting as a workaround after Chrome stopped supporting Manifest V2 extensions for normal users. Chrome 150, expected June 30, 2026, removes that flag. Chrome 151, expected in July 2026, removes more Manifest V2 flags, including ExtensionManifestV2Unsupported, ExtensionManifestV2Availability and AllowLegacyMV2Extensions.

A Google engineer cited maintenance cost, code complexity and security bugs tied to Manifest V2 in a Chromium code review. Google’s point has a clear engineering logic: Chrome developers do not want to carry old extension paths after the company has moved its supported extension model to Manifest V3.

Users see a different trade-off. Manifest V2 gave blockers more control over network requests. Manifest V3 moves more work into Chrome’s declarative rules system, which asks extensions to give Chrome rules in advance. Chrome then applies those rules. That model can reduce broad extension access, but it also limits how blockers react to hostile ad scripts, anti-blocking checks and site-specific breakage.

Raymond Hill, the developer behind uBlock Origin, has maintained uBlock Origin Lite for Manifest V3. Users can install it, but Hill has described it as a different product with fewer filtering options. That difference matters for users who depend on heavy custom lists or aggressive blocking modes.

Chrome users now face two practical choices. They can move to a Manifest V3 blocker such as uBlock Origin Lite, AdBlock, Adblock Plus or AdGuard’s Chrome-compatible version. They can also move to a browser that keeps stronger content-blocking support.

Firefox remains the clearest path for users who want uBlock Origin in its original form. Mozilla supports WebExtensions compatibility, and Firefox still gives blockers access to APIs that Chrome has removed or constrained. Some Chromium-based browsers may keep pieces of Manifest V2 support, but Google’s removal of old code from Chromium raises the cost for each browser vendor that wants to maintain it.

The change also sharpens a conflict inside Chrome’s business model. Google builds the world’s dominant browser and sells ads through the world’s dominant search advertising business. Chrome users who install blockers often want less tracking, faster pages and fewer intrusive ads. Publishers and advertisers want revenue from the open web. Google has to defend Chrome’s security model while users judge the result by whether their blockers still work.

Manifest V3 does solve some real browser risks. Extensions with broad access can inspect pages, rewrite traffic and collect sensitive data. Google can reduce that risk by narrowing extension power and moving more decisions into Chrome itself. The cost lands on developers who built sophisticated tools around the older model.

Chrome 150 and 151 turn a long migration into a hard cutoff for holdouts. Users who ignored earlier warnings will see old Manifest V2 blockers stop working as Google removes the last flags. Developers who support Chrome will build for Manifest V3. Users who want the old blocking model will need a browser that still supports it.