Ad-Verse: Google announced the transition from Manifest V2 browser add-ons a few years ago, but kept a few well-known "secrets" available to support legacy extensions. Now, Chromium developers have explained that MV2-based extensions are completely going away in just a few weeks.

Starting with the next major release, Chromium will stop supporting Manifest V2 extensions. The change will affect users who have clung to uBlock Origin in Chrome, Edge, and other major web browsers based on Chromium. Even Opera, despite stating otherwise, will soon lose this capability.

Chromium contributor Anton Bershanskiy recently highlighted how the newest Chrome release (149) is going to be the last offering some sort of MV2 compatibility. The developer quoted a recent commit by Chromium programmer Devlin Cronin, who stated that future releases are going to remove the "kExtensionManifestV2Disabled" feature from the engine's code base.

Cronin said that the ExtensionManifestV2Disabled feature has been default-enabled for more than a year, meaning Chromium-derived browsers were unable to use the "effectively-dead" compatibility code. The feature is part of a long list of tricks users and browser makers could employ to keep supporting MV2 add-ons, and according to Bershanskiy, the worst is yet to come.

A giant mega-corporation like Google cannot support a feature such as MV2 indefinitely, Cronin explained. Removing compatibility flags will allegedly improve the reliability and security of Chrome and Chromium, as MV2 code is now considered unwanted technical debt that is too complex to maintain.

After Chromium/Chrome 150 loses the kExtensionManifestV2Disabled flag, users will not be able to install MV2 extensions from the Chrome Web Store. Furthermore, Chrome 151 will remove the following additional methods users relied on to keep legacy add-ons working:

• ExtensionManifestV2Unsupported
• ExtensionManifestV2Availability
• AllowLegacyMV2Extensions

According to a recent message by uBlock Origin developer Raymond Hill, Opera will follow the same path as Chrome because Chromium is completely removing support for Manifest Version 2. Hill remarked how Opera's previous pledge was about continuing support for MV2 add-ons despite Google's decisions over the Chromium project.

Google started moving away from MV2 in 2024, asking Chrome users to replace older extensions with newer MV3 ones. Manifest V3 add-ons such as uBlock Origin Lite are allegedly more secure and easier to manage in the browser, but they cannot technically provide the same level of functionality available through MV2. Mozilla recently remarked that the team has no plans to abandon MV2, leaving Firefox and its Gecko layout engine as the sole platform offering full support for uBlock Origin and other security tools that cannot work with MV3.