Manifest V3 migration checklist

This page provides a quick reference to help you identify any changes you might need to make to an Manifest V2 extension so that it works under Manifest V3 (MV3). For more description of the nature of these changes see the MV3 migration guide.

API checklist #

There are some changes you may need to make based on changes to the API surface. This section lists these changes.

Do you have host permissions in your manifest?
Host permissions in MV3 are a separate element; you don't specify them in permissions or optional_permissions.

• Move host permissions into the host_permissions field in manifest.json.

Are you using background pages?
Background pages are replaced by service workers in MV3.

• Replace background.page or background.scripts with background.service_worker in manifest.json. Note that the service_worker field takes a string, not an array of strings.
• Remove background.persistent from manifest.json.
• Update background scripts to adapt to the service worker execution context.

Are you using the browser_action or page_action property in manifest.json?
These properties are unified into a single property in MV3.

• Replace these properties with action.

Are you using the chrome.browserAction or chrome.pageAction JavaScript API?
These two equivalent APIs are unified into a single API in MV3.

• Migrate to the chrome.action API.

Are you currently using the blocking version of chrome.webRequest?
This API is replaced by declarativeNetRequest in MV3.

• Migrate request modification logic to chrome.declarativeNetRequest rules.
• Replace the webRequestBlocking permission with declarativeNetRequest.
• Remove the webRequest permission if you no longer need to observe network requests.
• Remove unnecessary host permissions; blocking a request or upgrading a request's protocol doesn't require host permissions with declarativeNetRequest.

Are you executing remote code or arbitrary strings?
You can no longer execute external logic using chrome.tabs.executeScript({code: '...'}), eval(), and new Function().

• Move all external code (JS, Wasm, CSS) into your extension bundle.
• Update script and style references to load resources from the extension bundle.
• Use chrome.runtime.getURL() to build resource URLs at runtime.

Are you executing functions that expect an MV2 background context?
The adoption of service workers in MV3 isn't compatible with methods like chrome.runtime.getBackgroundPage(), chrome.extension.getBackgroundPage(), chrome.extension.getExtensionTabs(), and chrome.extension.getViews().

• Migrate to a design that passes messages between other contexts and the background service worker.

Security Checklist #

There are some changes you may need to make based on changes in security policy. This section lists these changes.

Are you making CORS requests in content scripts?

• Move these requests to the background service worker.

Are you using a custom content_security_policy in manifest.json?

• Replace content_security_policy with content_security_policy.extension_pages or content_security_policy.sandbox as appropriate.
• Remove references to external domains in script-src, worker-src, object-src, and style-src directives if present.