M365 Tenant to Tenant Migration.

Question

M365 Tenant to Tenant Migration.

Nakul Kaushik 0

We are currently performing an M365 Tenant-to-Tenant Migration and have moved a couple of users from Tenant A to Tenant B. After moving the users from Tenant A to Tenant B, we have provided the users with access to Teams Channels that are currently hosted in Tenant A.

Users can access the files and folders under Teams Channels, but they currently have to switch the directory from the Teams app. In other words, they are logged in to Teams using their Tenant B account, and from their profile, they need to switch to Tenant A to access the specific Teams Channels they have been granted access to.

I would like to understand how we can make the Tenant A Teams Channels visible under the Tenant B Teams experience, so that users can directly access those channels without having to switch between tenants.

Also, Tenant A and Tenant B currently have cross-tenant settings in place.

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Answer 1

Dear Nakul,

From my research, the behavior you are seeing is expected. Your migrated users are accessing Tenant A as guest users, and cross-tenant access settings on their own do not surface existing standard or private channels inside the Tenant B Teams experience. To make a channel visible while users stay signed in to Tenant B, Tenant A must use a shared channel with Microsoft Entra B2B direct connect. B2B direct connect lets users access an external organization's shared channel from their home Teams instance using their own credentials, without switching tenants. Both tenants must mutually enable it in their inbound and outbound cross-tenant access settings, as sharing will not work unless both sides allow it. The general process is:

Verify B2B Direct Connect is allowed in both directions between Tenant A and Tenant B.
Verify the relevant Teams channel policies permit users to participate in external shared channels.
In Tenant A, create a new channel with the Shared privacy type.
Share that channel with the migrated Tenant B users or an eligible Tenant B team.
Have the users access the shared channel while remaining signed into Tenant B.

There are two things that commonly trip this up in a migration scenario like yours. First, guests cannot be added to a shared channel, including guests whose user type has been converted to member. Since your users already have guest accounts in Tenant A, when adding them in the Teams admin center you must search using ext:******@domain.com so you pick up their Tenant B organizational account rather than the existing guest object. External participants must also be added by UPN if it differs from their email address. Second, if Tenant A has Conditional Access policies requiring MFA, you need to configure inbound trust settings to accept MFA claims from Tenant B, otherwise those users will be blocked when they try to open the channel.

On the existing channels, there is no conversion path. Standard and private channels cannot be converted to shared channels, and a shared channel is tied to its parent team and cannot be moved. So your practical options are:

Continue using guest access, which requires switching to Tenant A.
Create replacement shared channels in Tenant A and move the required conversations/files through an appropriately planned migration.
Migrate the affected teams and channels fully to Tenant B as part of the tenant-to-tenant project.

Before moving content, note that each shared channel has its own membership and associated SharePoint storage context. Test the design with one non-production shared channel before applying it broadly.

For reference:

B2B direct connect Microsoft Entra overview - Microsoft Entra External ID | Microsoft Learn

Shared channels in Microsoft Teams - Microsoft Teams | Microsoft Learn

I hope this information helps clarify the situation and provides you with workable solutions. Should you have any further questions or need additional assistance, please don't hesitate to reach out. I'm always happy to help. Have a wonderful day!

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Nakul Kaushik 0 Reputation points

2026-09-23T10:39:23.4433333+00:00

Hello Kai,

Thanks for your update. Currently Tenant A have Private Teams Channel, so what we can do.
Kai-L 19,920 Reputation points Microsoft External Staff Moderator

2026-09-23T19:11:11.33+00:00

Dear Nakul,

A private channel can only include people who are already members of the parent team, and external participation through B2B Direct Connect is not supported in private channels. They also cannot be converted into shared channels.

So for Tenant A's existing private channels, you have two realistic options:

Keep guest access. The Tenant B users stay as guests in Tenant A and must switch tenants in Teams to reach the private channel.

Create a new shared channel in Tenant A for the content that needs cross tenant access, then move the required conversations and files across, and share it with the Tenant B users through B2B Direct Connect.

If the goal is to retire Tenant A entirely, the cleaner path is to migrate the teams and channels into Tenant B as part of the migration project.