I cannot sign in to the desktop Teams app.

Lee Jasmine 0 Reputation points
2026-08-13T11:47:19.6166667+00:00

I was invited to join Teams from another organization, but I can't sign in using only the desktop app.

The error is as follows:
An error occurred. [4usp8]

Message: Access denied for the resource.

Tag: 4usp8

[current situation]

  • You can view it without any problems from the web app version.

My company has an MS account, but we haven't implemented Teams.

  • On the login screen, no other organization options are displayed; only my own email address is shown, and clicking it does not produce any response. The above error appears when I try to add another account and enter my email address.
  • When I check my access logs from the administrator screen, it appears that access is successful in the web browser version with "User Type: Guest" and "Cross-tenant enabled," but fails or is interrupted in the desktop application with "User Type: Member" and "Cross-tenant disabled."

[Measures already taken]

  • Clear Teams-related caches on your PC

Reinstall

Removed Teams and Microsoft generic credentials from Windows Credential Manager.

  • From the PC settings screen, disconnect and then reconnect the "organizational account".
  • Clear my account's session from the administrator account.
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  1. Michelle Nguyen 1,180 Reputation points Independent Advisor
    2026-08-13T12:30:38.6466667+00:00

    Hi @Lee Jasmine

    Thank you for providing the detailed sign-in logs and the troubleshooting steps you have already completed.

    Because Teams works in the browser but the desktop client records the account as User Type: Member with Cross-tenant access disabled, this appears to be an account or tenant-routing issue rather than a local Teams cache problem. The desktop client may be attempting to authenticate against your home organization first, where Teams has not been enabled, instead of using the guest account in the inviting organization.

    Please ask the administrators of both organizations to review the following:

    1.Your organization

    -Confirm that outbound B2B collaboration is allowed for the inviting organization.

    -Confirm that Microsoft Teams is not blocked by Conditional Access, tenant restrictions, or enterprise application settings.

    -If Teams is disabled through licensing or service configuration, temporarily enabling Teams for your account may allow the desktop client to complete home-tenant discovery.

    2.Inviting organization

    -Confirm that your account exists as User type: Guest, not Member.

    -Confirm that the guest account has been added to at least one Team. Microsoft notes that a guest must be added to a Team before guest functionality becomes available.

    -Review inbound cross-tenant access settings for your organization and ensure B2B collaboration and Microsoft Teams access are allowed. Cross-tenant settings control both inbound access to the resource tenant and outbound access from the user’s home tenant.

    -Review any Conditional Access policies applied to guest or external users.

    -If necessary, delete the existing guest object, wait for directory replication, and send a new invitation.

    Please do not sign in with the #EXT# guest address shown in Microsoft Entra ID. Continue using your normal work email address, because the guest object relies on your home organization for authentication.

    When testing again, open the invitation link in an InPrivate browser window, complete the invitation redemption, and then launch Teams from the web using Open in desktop app. These details will allow the administrators to identify which tenant or policy is denying the desktop-client token request. In the meantime, please continue using Teams on the web as a workaround.

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