Microsoft has set a July 2026 deadline that will affect any developer planning a new Teams Store listing for a channel-enabled app. Starting that month, new submissions must use manifest schema version 1.25 or later. But the rule is narrower than it first appears: it does not force existing apps to upgrade, nor does it apply to internally distributed packages.

A Targeted Requirement, Not a Blanket Mandate

Microsoft’s updated documentation for the Teams app manifest makes clear that the new rule is a submission gate for the public Store, not a universal upgrade command. As first reported by WindowsForum, the policy kicks in July 2026, but only for new Teams Store submissions where the app is designed to work within channels. Existing Store listings are untouched; tenant-only app catalogs and sideloading are not covered. This nuance is critical because many organizations maintain a mix of public, line-of-business, and development apps. Treating the announcement as a call to re-package every Teams package would waste resources and introduce unnecessary risk.

Digging Into the Manifest Change

The manifest schema version 1.25 introduces a dedicated capability declaration for shared and private channels: supportsChannelFeatures: "tier1". Standard channel support remains the default for apps with team scope. So if your app only needs to operate in standard channels, you can avoid the tier1 flag. But if you claim shared or private channel support, you must include that field. Microsoft’s documentation warns that simply adding the declaration isn’t enough; publishers must test actual behavior in those channel types.

The July 2026 deadline applies simultaneously: new Store submissions for channel apps must hit manifest 1.25, and if the app targets shared/private channels, it must declare tier1. This is a combined compliance point for publishers.

What It Means for You

For Developers Preparing New Store Submissions

If you’re about to submit a fresh Teams Store app that works in channels—whether as a tab, bot, messaging extension, or meeting app—you need to act now. The manifest file must be version 1.25 or later. For apps that will support shared or private channels, include supportsChannelFeatures: "tier1". Don’t leave this to the last submission step; integrate it into your build pipeline. Test thoroughly in the actual channel types you claim, because the Store validation will likely check the capability declaration. A mismatch could delay your listing.

For IT Administrators and Internal App Owners

Most internal line-of-business apps and tenant-only deployments are not affected by this deadline. Unless you plan to publish an app to the public Store, the July 2026 date does not force you to upgrade manifests. However, that doesn’t mean you can ignore it forever. Use the occasion to audit your app inventory. Identify apps that might someday go public, or that already support shared/private channels. Schedule manifest updates as part of normal maintenance cycles, not as a panic-driven project. Keep in mind that tenant catalog and sideloaded apps still need to be tested if they claim channel capabilities, even without a Store submission.

For Publishers of Existing Store Apps

If your app is already in the Teams Store, Microsoft is not requiring an immediate republishing solely to bump the manifest version. The requirement only applies to new submissions. But watch for future guidance—Microsoft could extend the rule to updated submissions later. Meanwhile, if you plan to add shared/private channel support to an existing app, your next submission will need to meet the 1.25 standard. Plan ahead.

How We Got Here

Teams has steadily expanded its channel model. Standard channels came first, then private channels, and later shared channels for cross-organizational collaboration. Each channel type brings unique membership, access, and behavior quirks. Earlier manifest versions didn’t formally distinguish between channel types. Developers often assumed that an app working in a standard channel would sail through in a private one—then hit unexpected permission errors or UX glitches. Microsoft needed a way to force publishers to declare intent and test accordingly. Enter manifest 1.25 and the tier1 declaration.

The July 2026 deadline acts as a forcing function. It says: from this point forward, we will no longer accept new Store apps that claim channel support without meeting this baseline. It aligns the platform’s governance with its evolving feature set. This is not the first time Microsoft has used a manifest version bump to enforce capability checks—familiar to Office Add-in and SharePoint Framework developers—but it’s the most pointed for Teams channel scenarios.

What to Do Now: A Practical Triage

Rather than launching a mass manifest-upgrade effort, teams should follow these steps:

  1. Inventory your apps: List every Teams app your organization develops or maintains, including vendor-built custom solutions.
  2. Map distribution routes: For each app, note whether it’s headed for a new Teams Store submission, already published, deployed only in your tenant catalog, or sideloaded for testing.
  3. Identify channel scope: Determine if the app is channel-enabled and which channel types it actually uses. Standard channels are the default; shared/private require explicit declaration.
  4. Prioritize based on Store plans: Only apps with a new Store submission planned need immediate manifest upgrades. Put them in a first-action bucket.
  5. For Store-bound apps: If channel support includes shared/private, set supportsChannelFeatures to "tier1". Verify the manifest version is 1.25 or higher.
  6. Test thoroughly: Even for standard channels, run your app through all target channel types. Don’t confuse publishing compliance with real-world functionality.
  7. Schedule internal updates: For tenant-only apps, plan manifest and testing updates during regular sprints. No rush, but don’t kick the can down the road indefinitely.

This triage produces a focused remediation list rather than a sprawling “upgrade everything” panic. A small number of apps will likely need immediate attention, while the majority can be handled on a business-driven timeline.

The Bottom Line

Microsoft’s July 2026 manifest rule is surgical, not sweeping. It targets new public Store submissions for channel apps, closing a gap that has caused inconsistent behavior in shared and private channels. The key is to read the policy precisely and act only where it bites. Confuse it with a tenant-wide deadline, and you’ll burn cycles fixing apps that were never in scope. For the small set of apps heading to the Store with channel ambitions, the clock is ticking—but the work is well-defined. For everyone else, stay informed, keep testing, and align manifest upgrades with your normal release cadence.