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Raf's avatar
Raf
Copper Contributor
Dec 02, 2025

Teams B2B sync on macOS

Hi all,

I have set up B2B collaboration between two Microsoft 365 tenants. Each tenant has its own Teams environment and users can switch tenants inside the Teams app without any problems. Both sides would like to work in each other's Teams channels and they also want something very specific. They want OneDrive on macOS to sync both their own tenant’s files and the other tenant’s files locally in Finder.

This is where things break.

  • Everything looks correctly configured.
  • B2B collaboration is enabled on both tenants
  • Guest access is allowed
  • Sharing settings are set to the least restrictive level

When a user opens a SharePoint library in the other tenant and clicks Sync, the OneDrive popup shows up and macOS asks to open the OneDrive app, but then nothing happens. No new library appears in OneDrive and there is no error.

My question is whether this is simply an expected limitation. Can OneDrive on macOS actually sync document libraries from a different tenant when the user is only a B2B guest? Or is this not supported?

I have seen mixed information. Some people say guests cannot sync cross tenant libraries at all. Others say it only works when the team is set up as a Shared Channel. Before restructuring everything I want to confirm the real behaviour.

Do I need to create a Shared Team or Shared Channel to make cross tenant file sync work in Finder? Or is the missing sync just how OneDrive behaves for B2B guests on macOS?

Any real world experience would be very helpful.

community

1 Reply

  • Surya_Narayana's avatar
    Surya_Narayana
    MCT
    Dec 04, 2025

    hi Raf​ what you’re seeing is expected behavior. With classic B2B guest access, OneDrive on macOS cannot sync document libraries from another tenant. The “Sync” button will appear, OneDrive will open… and then nothing happens. That part is not a bug — it’s a limitation.

    What works

    Users can:

    • Switch tenants in Teams
    • Access files in SharePoint/Teams via browser
    • Edit files online
    • Use “Add shortcut to OneDrive”

    What does not work (by design)

    With regular B2B guest accounts:

    • OneDrive on macOS (and Windows) cannot sync external tenant libraries
    • Libraries won’t appear in Finder via OneDrive
    • No clear error is shown

    That part is not supported today for B2B guests.

    When DOES cross-tenant sync work?

    It works only if you use:

    Microsoft Teams Shared Channels (B2B Direct Connect)

    This uses Entra ID B2B Direct Connect instead of guest accounts.

    With Shared Channels:

    • Users stay in their own tenant identity
    • Access the other tenant’s Team/Channel & SharePoint library
    • OneDrive on macOS CAN sync the library to Finder
    • This is fully supported by Microsoft

    Regular teams/shared folders will NOT work. Only Shared Channels.

    If requirement = “Files from both tenants must show up in Finder via OneDrive”
    You must use Shared Channels, not classic B2B guests

    If requirement = “Browser access is enough”
    B2B guests are fine

    If requirement = “Seamless cross-tenant sync & collaboration”
    Use B2B Direct Connect + Shared Channels

    Recommendation

    Configure B2B Direct Connect in Entra ID (both tenants)

    Create a Teams Shared Channel

    Invite users as members, not guests

    Files live in the resource tenant SharePoint

    Users click Sync → Works in OneDrive + Finder

    This avoids creating guest accounts and allows proper syncing on macOS.

    Do I need to create a Shared Team or Shared Channel?

    Yes. Specifically a SHARED CHANNEL.

    Anything else will continue to fail silently — that’s expected behavior.

     

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