Chrome is pulling the plug on Manifest V2 extensions. In Chromium 150, the ExtensionManifestV2Disabled flag was removed. Chromium 151 will kill off ExtensionManifestV2Unsupported, ExtensionManifestV2Availability and likely AllowLegacyMV2Extensions. That means hacks like the Windows Registry tweak to keep uBlock Origin alive will stop working after version 151. Google engineer Devlin Cronin says the code is dead weight, full of security bugs and too complex to maintain. Other Chromium-based browsers are lining up behind Chrome. Microsoft Edge began blocking uBlock Origin in February. Opera said back in October 2024 it would keep MV2 longer, but internal mail and user reports suggest it’s eyeing the same sunset. Opera’s blog post from September 2025 reassures users that installed MV2 add-ons still work for now, but it won’t accept new MV2 uploads and will phase out less-used extensions once its MV3 store is ready. Brave and perhaps Vivaldi remain the only browsers still backing MV2 indefinitely. If you need a blocker on Chrome today, uBlock Origin Lite on MV3 is the short-term answer, but it doesn’t match the original’s performance. Firefox stands out as the plug-in platform that supports both MV2 and MV3 without drama. Developers of popular MV2 extensions face a clear deadline: update to MV3 or watch your user base shrink as Chromium browsers turn off the legacy APIs.