Microsoft has set a July 2026 deadline that will reshape how developers submit channel-enabled apps to the Teams Store. Starting that month, all new store listings that work within Teams channels must use manifest schema version 1.25 or later. The requirement was embedded in a Microsoft Learn page on publishing Microsoft 365-enabled Teams apps, where it’s easy to miss among broader distribution guidance. But for marketplace publishers, it’s a concrete engineering checkpoint with practical implications.

What Actually Changed

The specific language from Microsoft reads: “Starting July 2026, if your app is channel-enabled, all new Teams Store submissions must use manifest schema version 1.25 or later.” Manifest 1.25, which became generally available in January 2026, introduces a key field: supportsChannelFeatures. This opt-in declaration tells Teams that the app is ready to operate within private and shared channels—environments where membership, file access, and data boundaries differ from standard channels.

A channel-enabled app is any app that surfaces in a channel context, such as a tab, bot, or message extension that can be added to a team’s channel. If you’re submitting such an app for the first time through the Teams Store after June 2026, you won’t pass validation unless your manifest declares version 1.25 and sets supportsChannelFeatures to a value like "tier1". The manifest change itself can be small. For a straightforward app that doesn’t depend on team membership or files, the update might look like this in the JSON:

{
  "manifestVersion": "1.25",
  "supportsChannelFeatures": "tier1"
}

However, this isn’t a simple version-number bump. It’s a declaration that the app has been tested across standard, private, and shared channels and behaves correctly. Microsoft’s documentation notes that the simple route only applies when the app doesn’t rely on team or channel membership for permissions, doesn’t handle files stored in Teams or SharePoint, doesn’t combine data across channels, and doesn’t treat internal users differently from guests. If any of those conditions aren’t met, the migration requires a deeper audit of application logic.

Crucially, the requirement is scoped to new Store submissions. Existing apps already in the Store are not immediately forced to upgrade, though any update or resubmission after July 2026 might trigger the validation. Microsoft hasn’t spelled out exactly how it will handle existing listings, so publishers should prepare now to avoid last‑minute scrambles. Also, the rule only applies to the commercial marketplace (Microsoft AppSource); apps distributed solely within a single tenant (via Teams admin center, Developer Portal, or other internal routes) are not directly captured by this gate. But ignoring it would be shortsighted if those internal apps ever need to support private or shared channels.

What It Means for You

For Marketplace Publishers

If you’re building a new channel‑enabled app listing for the Teams Store, you must adopt manifest 1.25 now. That means more than editing JSON—you’ll need to test how your app handles the reduced membership of a private channel, the cross‑tenant boundaries of a shared channel, file storage nuances, and user identity differences. Use the Teams Developer Portal to validate your package before submission.

For Internal Developers

You’re not bound by the July 2026 Store deadline, but you should still consider moving to 1.25 if your app is used in private or shared channels. If an app operates exclusively in personal scope (e.g., a message extension that doesn’t rely on channel context), you’re exempt. But many internal apps have grown organically and may have outdated scopes in their manifest. This is a good time to audit and clean up.

For IT Administrators

Start an inventory now. Classify every Teams app in your tenant by distribution (Store vs. custom), channel capability, and manifest version. Even if an app isn’t headed to the Store, a future platform update could require newer manifests for channel features. Check your Teams app permission policies and custom app settings to ensure they align with whatever manifest changes your developers make.

For End Users

The impact is indirect but positive. As more apps properly declare their channel readiness, you’ll see fewer glitches when using tabs or bots in private channels. The change should lead to more predictable behavior and fewer “this app doesn’t work here” surprises.

How We Got Here

Teams manifest versions have evolved steadily. Version 1.13 was a milestone that enabled Teams apps to run across Microsoft 365 (Outlook, Office). As Teams gained private channels (2019) and shared channels (2022), the platform needed a way for apps to signal that they understand these new contexts. In a standard channel, all team members have access; in a private channel, only a subset; in a shared channel, participants may come from different organizations. An app that naively assumed “channel members” equals “team members” could leak data or break.

Microsoft introduced supportsChannelFeatures in manifest 1.25 to give developers a formal way to opt into these capabilities. The “tier1” level is the baseline declaration. Future tiers may unlock more advanced scenarios. By tying the declaration to a Store submission requirement, Microsoft is ensuring that new marketplace apps are built with channel awareness from day one. The July 2026 date gives developers a full year after the manifest’s general availability to adapt.

What to Do Now

  1. Classify your app. Is it a new Store submission? Is it channel-enabled? If both are yes, proceed with the 1.25 migration. If it’s existing, consider moving early. If it’s internal-only and channel-enabled, evaluate whether private/shared channel support is needed.
  2. Audit application logic. Go beyond the manifest. Trace how your app uses team membership, channel membership, file storage, cross-channel data, and user type. Document each assumption. If your app assigns tasks based on team roster, it might need to restrict to channel roster in private channels.
  3. Update the manifest. Change manifestVersion to "1.25" and add supportsChannelFeatures. The simplest valid value is "tier1", but read the documentation carefully. Remove any unused scopes that might confuse validation.
  4. Test thoroughly. Deploy to a test tenant with private and shared channels. Verify tabs render data only for the correct users. Test bots and message extensions in those channels. Check file operations. Test with guest and external participants.
  5. Validate. Use the Teams Developer Portal’s validation tool before submitting to the Store. It will catch schema errors and may flag common issues.
  6. Plan for existing Store apps. Even if not mandatory today, start a branch with manifest 1.25 and run the same tests. When you eventually need to update the app for any reason, you’ll be ready.

Outlook

Microsoft’s documentation leaves some gray areas—most notably how it will handle updates to existing Store listings. Expect further clarification as the deadline nears. There’s also the possibility that manifest 1.25 will become required for non-channel apps later, or that single-tenant distributions will face similar gates. The smarter move is to see this not as a one-time fire drill but as a push toward better channel hygiene. Teams is leaning hard into flexible collaboration spaces, and apps that don’t respect channel boundaries will increasingly feel broken. By getting ahead of the deadline, developers and admins can turn a compliance checkbox into a real quality improvement.