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What you need to check
Browser extensions have two different version fields that are easy to confuse:
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manifest_versionidentifies the manifest format. The value2is Manifest V2;3is Manifest V3.versionis the extension maker’s release number, such as4.2.1. It does not identify V2 or V3.
Microsoft describes manifest.json as the extension’s JSON blueprint and lists manifest_version as a required field in its Manifest file format documentation. Therefore, reading that field in the package you actually have installed is the reliable answer.
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Choose a checking method
| Method | What it tells you | Certainty | Access needed |
|---|---|---|---|
edge://extensions |
Finds the extension, ID and ordinary release version; may show a V2 warning | Not definitive by itself | Any Edge profile where the extension is installed |
Installed manifest.json |
Reads the format declared by the installed package | Definitive for that package | Access to the profile’s extension files |
Source manifest.json for an unpacked extension |
Reads the format of the local development copy | Definitive for that source directory | Access to the directory used when loading the extension |
Step-by-step: check an installed extension on Windows
-
Open Microsoft Edge and enter
edge://extensionsin the address bar. -
Find the extension by name. If several extensions have similar names, note the extension ID shown on the card. Microsoft’s distribution documentation explains that the ID and extension version are available on this page after a packed extension is loaded; see Alternative ways to distribute an extension.
-
Open the active Edge profile’s extension directory. The common Windows pattern is:
%LOCALAPPDATA%MicrosoftEdgeUser Data<profile>ExtensionsMicrosoft Q&A shows the equivalent expanded form as
C:UsersusernameAppDataLocalMicrosoftEdgeUser DataprofilefolderExtensions. Replace the account name and profile folder with the values on your computer. The usual profile folder is often aDefault-style name, but use the profile that is currently running the extension.Special offer. See more information about Outbyte and uninstall instructions. Please review EULA and Privacy policy. -
Inside
Extensions, locate the folder whose name matches the extension ID fromedge://extensions. An extension can have more than one installed version directory, particularly after an update. -
Open the version directory you need and locate
manifest.json. Open it in a text editor that displays plain text and search formanifest_version. -
Record the value exactly. For example:
{ "manifest_version": 2, "version": "4.2.1" }This package is Manifest V2 even though its release number is
4.2.1. A value of3is Manifest V3.
The installed files are tied to the Edge profile. If you use more than one profile, repeat the check in each profile that has the extension. Matching the ID prevents you from reading a similarly named extension or the wrong version directory.
How to interpret the manifest without mixing up the fields
manifest_version is the answer
Look for the key written exactly as manifest_version. Microsoft’s manifest specification requires this field and uses it to distinguish the manifest formats. The values relevant to this check are:
Value in manifest.json |
Meaning |
|---|---|
2 |
Manifest V2 |
3 |
Manifest V3 |
version is only the release number
Do not infer the manifest format from a release such as 2.0, 3.5.0 or 4.2.1. Those numbers belong to the extension’s own release sequence. A high release number can still use V2, and a low release number can use V3. Only the manifest_version value answers the format question.
Checking an unpacked or locally developed extension
An unpacked extension is loaded from a directory you or an administrator selected, rather than from a store-installed package. In that case, do not search the profile’s store cache first. Open the source directory used for the extension and inspect its manifest.json directly.
- Go to
edge://extensionsand identify the unpacked extension. - Use the extension’s management controls or your development notes to identify the directory from which it was loaded.
- Open that directory’s
manifest.jsonand readmanifest_version.
Microsoft’s sideloading guidance describes loading an extension from a directory containing its source files, including manifest.json. The source file is the relevant manifest for that unpacked copy; an unrelated packed copy elsewhere may have a different format.
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What edge://extensions can—and cannot—tell you
What the page is good for
The extensions page is the fastest way to find the installed name, ID and ordinary extension version. Those identifiers let you select the correct folder and version directory when you inspect local files. It is also the place where Edge may display deprecation messaging.
Why the warning is not a complete test
Microsoft’s current migration timeline says Manifest V2 deprecation warnings are scheduled to appear for some users on the Manage extensions page from mid-September 2026. Because the published wording says “some users,” the warning is a signal, not a universal inventory. An extension can be V2 even when no warning is visible, and a warning does not replace reading the installed manifest. The timeline is published in Microsoft’s Timeline for migrating to Manifest V3, updated September 15, 2026.
Developer mode is not required for this check
You do not need to turn on developer mode merely to open a local file and read its manifest. Microsoft documents a policy that can allow or block users from enabling developer mode on supported Windows and macOS versions 128 and later; details are in ExtensionDeveloperModeSettings. That policy can affect development workflows, but it does not change the value written in an extension’s manifest.json.
Edge’s Manifest V2 migration timeline
The dates below describe Microsoft’s published plan as of October 13, 2026. They are migration milestones, not proof of the format used by any particular extension.
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1Clear out junk files and repair common Windows errors2Scan for outdated or missing drivers - takes under a minute3Repair Windows errors before they cause bigger problems| Date or period | Published milestone | What it means for your check |
|---|---|---|
| July 2022 | Partner Center and the Microsoft Edge Add-ons website stopped accepting new Manifest V2 extensions. | An older installed extension can still be V2; this date does not convert existing installations. |
| August 2026 | Partner Center began displaying a Manifest V2 deprecation warning for extensions that still use V2. | A warning in a developer or publisher workflow is evidence of a flagged V2 extension, not a replacement for inspecting your installed copy. |
| Mid-September 2026 | Warnings were scheduled to appear for some users on Edge’s Manage extensions page and at the Microsoft Edge Add-ons website. | Warning availability can vary by user, so its absence is not proof of V3. |
| Early 2027 | Manifest V2 deprecation is expected to begin for enterprise customers. | Managed environments should verify extension formats before that stage rather than waiting for a block. |
| Other dates | Some dates, including when Edge Add-ons will stop accepting updates to remaining V2 extensions, are listed as unspecified. | Do not treat an unspecified date as a completed policy change. |
Microsoft advises developers whose extensions still use V2 to migrate to V3 and submit the migrated version through Partner Center. A migration announcement does not prove that an installed extension has already updated; the local manifest_version remains the per-extension test.
Managed devices: policy can affect use without changing the format
On company-managed computers, Edge policy can determine whether a V2 extension is allowed to run. Microsoft’s ExtensionManifestV2Availability policy supports these modes:
| Policy mode | Effect described by Microsoft |
|---|---|
Default |
Uses the browser’s default behavior. |
Disable |
Disallows Manifest V2 extensions. |
Enable |
Allows Manifest V2 extensions. |
EnableForForcedExtensions |
Allows force-installed V2 extensions while other V2 extensions are disabled. |
The policy applies on Windows and macOS from Edge 123. Microsoft lists Android and iOS as unsupported for this policy. A policy decision answers “can this V2 extension run here?” It does not answer “is this package V2?” Read manifest_version for the latter.
Troubleshooting when the check does not work
You cannot find the extension folder
Confirm that you are looking in the profile currently running the extension and that the folder name matches the ID shown in edge://extensions. The Windows pattern above is for the local Edge profile; Microsoft’s published example does not establish one universal file location for every operating system. On another operating system, use the extension’s source directory if it is unpacked or consult your organization’s deployment documentation.
There are several version folders
Use the version directory corresponding to the package currently shown as installed in Edge. If you are auditing an earlier package for change history, inspect each directory separately and record its manifest_version; do not assume that an update kept the same format.
You see a warning but cannot access the files
Record the extension name and ID from edge://extensions, then ask the device administrator or support team for the installed package’s manifest. Managed permissions may prevent local file access or may disable the extension before you can test it. The warning still does not reveal the ordinary release number’s meaning; the required field remains manifest_version.
The extension was loaded from a local directory
Inspect the directory used to load it, not a similarly named store installation. A locally edited manifest can differ from a packaged release, so identify which copy is active before recording the result.
How to make the result auditable
If you are checking one extension for yourself, recording the field may be enough. For a household, support desk or enterprise inventory, keep a small record for every profile and package. Start with the date of the check, the Edge profile name, extension name, extension ID and ordinary release version shown on edge://extensions. Then add the path or source directory you inspected, the version-directory name, and the exact value of manifest_version.
Keeping both version fields prevents a later reader from confusing a release update with a manifest migration. For example, an entry can state “ID: extension ID, release version: 4.2.1, manifest_version: 2.” If the extension later updates to a different directory, make a new entry rather than overwriting the old one. This shows whether the format changed with the update.
For an unpacked extension, record the source directory and identify who controls it. A developer can change that file without changing a store package, so the result applies only to the copy loaded from that directory. If the same name appears as both an unpacked extension and a store installation, keep separate records and use the IDs and locations to distinguish them.
Common interpretation mistakes
- Using the release number as the format. A release beginning with “2” or “3” is not evidence of V2 or V3. Read the separate manifest field.
- Treating a missing warning as a clean result. Warnings are being shown to some users, not necessarily everyone. No warning can mean only that the message is not being displayed in that account or build.
- Checking the add-ons website instead of the installed copy. A listing or a newly submitted package may not match the package currently installed in a particular profile.
- Opening the wrong profile. Edge profiles have separate extension installations. Match the extension ID and use the profile that is active when you see the extension.
- Reading an old version directory. Updates can leave more than one directory. Select the directory for the package Edge currently reports as installed.
- Assuming policy changes the manifest. A policy can permit, disable or selectively allow V2 extensions, but it cannot turn a V2 manifest into a V3 manifest.
- Turning on developer mode unnecessarily. Viewing a manifest file does not require developer mode. A policy may block developer mode, yet you can still use the appropriate local file or request the package from an administrator.
Which checking approach should you use?
Use the extensions page first when convenience matters: it gives you the name, ID and release version in one place. Use the installed manifest when certainty matters: it states the format of the package Edge has installed in that profile. Use the source manifest for an unpacked extension because the profile’s cached store files may not represent the active local copy.
Access is the practical limitation. The Windows profile-files method requires permission to reach the local application-data directory and to read the package files. On a managed computer, administrators may restrict those actions or disable the extension before you can inspect it. In that situation, the correct escalation is to provide the extension ID and request the installed manifest or an inventory result from the device administrator. Do not substitute a release number or a general warning for that evidence.
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- Open
edge://extensions. - Record the extension name and ID.
- Note the ordinary
versiononly as an identifier; do not use it to classify V2 or V3. - For a Windows installation, open
%LOCALAPPDATA%MicrosoftEdgeUser Data<profile>Extensions. - Open the folder matching the ID, then the relevant installed-version directory.
- Open
manifest.json. - Read
manifest_version:2is V2 and3is V3. - If the extension is unpacked, inspect the source directory’s manifest instead.
- If Edge shows no warning, do not mark the extension V3 without the manifest check.
- On a managed device, treat policy status and manifest format as separate records.
Bottom line
Use edge://extensions to identify the right extension, but open its actual manifest.json for a definitive answer. The value manifest_version: 2 means Manifest V2; manifest_version: 3 means Manifest V3. Warnings, release numbers and policy settings provide context, not a substitute for that field.
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Frequently Asked Questions
Can I tell from an Edge warning that an extension is Manifest V2?
A warning is useful evidence that Edge or the Add-ons service has flagged the extension, but it is not a complete test. Microsoft says warnings are shown to some users from mid-September 2026, so an extension can be V2 without a visible warning. Open the installed manifest and read manifest_version for certainty.
Does an extension version such as 4.2.1 mean it uses Manifest V2?
No. That is the extension’s release number. The format is identified only by manifest_version: 2 means V2 and 3 means V3.
Where is the Edge extension manifest on Windows?
For a store-installed extension, check %LOCALAPPDATA%MicrosoftEdgeUser Data<profile>Extensions. Open the folder matching the ID shown on edge://extensions, then the relevant version directory and its manifest.json file.
What if I have several Edge profiles?
Extension files are tied to the profile. Check each profile that contains the extension, and match the ID from that profile’s edge://extensions page before opening a folder.
How do I check an unpacked extension?
Inspect the manifest.json in the source directory from which the extension was loaded. That file describes the active unpacked copy; a similarly named store installation may have a different manifest.
Do I need to enable developer mode?
No. Developer mode is not required simply to read a local manifest file. Microsoft has a policy that can allow or block developer mode on supported Windows and macOS versions 128 and later, but that policy does not change the manifest value.
Can Edge policy make a V2 extension run even though it is still V2?
Yes. The ExtensionManifestV2Availability policy can use Default, Disable, Enable or EnableForForcedExtensions. Policy determines whether the extension is allowed to run; manifest_version determines its format.
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When will Manifest V2 deprecation affect enterprises?
Microsoft’s published timeline says deprecation is expected to begin for enterprise customers in early 2027. Some other dates, including when Edge Add-ons will stop accepting updates for remaining V2 extensions, are still listed as unspecified. Verify installed manifests rather than waiting for a block.
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