Chrome v142 removes uBlock Origin workaround, ending MV2 support

Chrome v142 eliminated the “Allow legacy extension manifest versions” flag, instantly disabling Manifest V2 extensions such as uBlock Origin for all desktop users [1]. The change ends the last official workaround that let ad‑blockers survive Chrome’s shift to Manifest V3, a move that threatens the functionality of many privacy‑focused extensions.

Chrome’s final MV2 kill switch

Chrome v142, which began rolling out in early November 2025, stripped out the legacy flags that developers and power users relied on to keep MV2 extensions operational after Chrome v139’s transition to Manifest V3 [1]. Without the flag, extensions like uBlock Origin are automatically disabled, and the only remaining method is a manual command‑line tweak that adds --disable-features=ExtensionManifestV2Unsupported,ExtensionManifestV2Disabled to the Chrome shortcut [1]. This approach is fragile and will likely break with future updates, signaling the end of official MV2 support.

Broader market implications

Google’s migration to Manifest V3 began in 2019 and was accelerated in Chrome v139 (late 2024), cutting off the Web Request API that ad‑blockers depend on [2]. The upcoming Chrome 150 and 151 releases, slated for late June and July 2025, are expected to cement the transition, removing any remaining workarounds [2]. Competing Chromium browsers such as Microsoft Edge and Opera are poised to follow Chrome’s lead, though Opera has hinted it may retain MV2 support “as long as it’s technically reasonable” [2]. Users seeking robust ad‑blocking are thus pushed toward alternatives like Firefox, which still supports MV2, or newer MV3‑compatible versions such as uBlock Origin Lite [2][3].

What to watch

• Chrome 150 rollout – scheduled for June 30 2025; expected to finalize MV3 enforcement [2].
• Extension developer response – monitoring whether uBlock Origin or other ad‑blockers release stable MV3 versions that match MV2 performance.
• Competitor browser policies – watching Opera’s statements and Edge’s roadmap for potential MV2 extensions support.

The removal of MV2 flags in Chrome v142 marks the definitive end of a work‑around that kept legacy ad‑blockers alive for years, forcing the ecosystem toward newer, less flexible MV3 extensions or a shift to alternative browsers. The next Chrome releases will confirm whether any residual compatibility remains.