5 minute read

Whether an extension still runs depends on two things: the Manifest version it was built on and the Chrome version you use. Chrome’s official timeline says Chrome 138 disabled Manifest V2 (MV2) extensions everywhere on July 24, 2025, and that MV2 extensions cease to function for anyone upgrading to Chrome 139 or later. It also says all remaining MV2 extensions were removed from the Chrome Web Store on August 31, 2026. This page explains how to check where your extensions stand.

Checked October 16, 2026 against Chrome’s timeline page, last updated September 9, 2026. The Brave and Edge details were re-checked on October 21, 2026.

Where MV2 extensions stand today

Your browser What happens to MV2 extensions
Chrome 139 or newer They do not run, per Chrome’s timeline
Chrome 138 or earlier Extensions installed before keep running, but they cannot update and cannot be reinstalled if removed, per Chrome
Firefox Mozilla says it keeps MV2 alongside Manifest V3
Brave and Edge Brave says on its blog that it hosts uBlock Origin and other MV2 extensions on its own servers, and Microsoft says Edge began moving users off MV2 in August 2026, aiming to finish the consumer transition by the end of 2026, per its Edge blog

If an extension stopped working after you updated Chrome, the likely reason is that it was an MV2 extension. That is an inference from the timeline, not something Chrome tells you in the extension list, so confirm it with the checks below.

How to check as a regular user

Open chrome://extensions in the address bar. Chrome’s timeline describes what that page showed during the phase-out. From June 2024 some users saw a warning banner there saying that some MV2 extensions would soon no longer be supported, and from October 2024 Chrome began disabling installed MV2 extensions in the stable channel and sent users to the Web Store to see recommended MV3 alternatives. The sources checked do not say whether those banners still appear in current Chrome versions.

A practical way to read the page now:

  1. Look for extensions that are turned off or flagged as unavailable.
  2. Search the extension’s name in the Chrome Web Store. If the listing is gone, it may have been one of the MV2 extensions removed on August 31, which is an inference rather than a Chrome statement.
  3. Look for an MV3 version from the same developer. For ad blockers, see our guide to MV3 alternatives.

How to check the manifest file

If you have an extension’s files, or you are the developer, open its manifest.json and find the "manifest_version" key. A value of 2 means a Manifest V2 extension, and a value of 3 means Manifest V3. Chrome’s migration guide has a step for updating the manifest.

What changed between MV2 and MV3

Chrome’s own overview lists three main changes:

  • Service workers instead of long-lived background pages. MV2 extensions had a background page that took up resources even when the extension was not running. In MV3, the background context runs only when needed.
  • No remotely hosted code. An extension can only execute JavaScript included in its own package, which is subject to Chrome Web Store review.
  • A new way to modify network requests. Chrome deprecated the blocking version of the webRequest API and offers the declarativeNetRequest API as what it calls a safer alternative for many use cases. Extension makers, especially ad blockers, say it is more limiting. Our hub page and MV3 explainer cover both views.

If you are a developer

Chrome’s migration overview and checklist are the reference. There is also an open-source Extension Manifest Converter in the GoogleChromeLabs GitHub organization. Its repository says it helps convert an extension to MV3 using search-and-replace changes, that it does not fully automate the conversion, and that it is not an official Google product. The repository was archived on April 19, 2026 and is now read-only, so treat it as a starting point at most.

Questions readers ask

How do I know if a Chrome extension uses Manifest V2? As a regular user, open chrome://extensions and look for extensions that are turned off or flagged as unavailable, then search the name in the Chrome Web Store. If you have the files or are the developer, open manifest.json and check the manifest_version key: 2 means Manifest V2 and 3 means Manifest V3.

Why does my extension say it is no longer available? Chrome’s timeline says all remaining MV2 extensions were removed from the Web Store on August 31, 2026. If the listing is gone, the extension may have been one of them, which is our inference and not a Chrome statement.

Do MV2 extensions still run in my Chrome? Not on Chrome 139 or newer. On Chrome 138 or earlier, extensions installed before keep running but cannot update and cannot be reinstalled if removed, according to Chrome.

Which browsers still support MV2? Mozilla says Firefox keeps MV2 alongside MV3. Brave says it hosts uBlock Origin and other MV2 extensions on its own servers. Microsoft says Edge began moving users off MV2 in August 2026 and aims to finish the consumer transition by the end of 2026.

Is there a tool that converts an MV2 extension? There is an open-source Extension Manifest Converter in the GoogleChromeLabs organization. Its repository says it uses search-and-replace changes, does not fully automate the conversion and is not an official Google product, and it was archived on April 19, 2026.

Update log

  • October 16, 2026: checked against Chrome’s timeline page, last updated September 9, 2026.
  • October 21, 2026: the Brave and Edge details were re-checked.
  • November 3, 2026: added the readers’ questions above. No facts were changed.

Sources:

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