"Make sure you're signed in to Teams" for user with True Delegate permissions

JamesSec@LCF 30 Reputation points
2026-01-06T21:35:36.3666667+00:00

Hoping someone here can give me some guidance, I've been stuck on this issue for some time now.

We have a user (who I'll call User 1 for convenience) that is trying to schedule a Teams meeting on another user (User 2)'s Outlook calendar. User 1 is able to start creating the meeting, but when he presses the Teams Meeting button in the ribbon provided by the Teams Add-In for Outlook to create the Teams meeting link and such, he receives the message "To schedule a Teams meeting, make sure you're signed in to Teams", even though he is already signed into the Teams client. Here is some info on our environment for reference:

  • Both users' mailboxes reside on an on-prem Exchange 2019 server
  • Both users are using Office 2021 LTSC
  • Both users are using Windows 11 24H2

We have tried a multitude of solves for this with no luck so far:

  • Gave User 1 "True Delegate" permissions on User 2's calendar (File > Account Settings > Delegate Access)
  • Removed and re-added User 1 to "True Delegate"
  • Ensured User 1 has Author permissions on User 2's Calendar
  • Removed and re-added User 1 from Author permissions
  • Uninstalled and re-installed the Teams Meeting Plugin for Outlook
  • Signed User 1 into a new computer and tried from a fresh install of Outlook
  • Rebuilt User 1's Outlook profile
  • Uninstalled and re-installed the Teams client (via teams bootstrapper)
  • User 1 receives the same error when trying to schedule a Teams meeting on anyone else's calendar other than his own

Does anyone have any suggestions as to what might be wrong here? It seems account-based, but all of his permissions look fine from Exchange.

Outlook | Windows | Classic Outlook for Windows | For business

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Answer accepted by question author
Anonymous
2026-01-07T04:10:41.3233333+00:00

Hi JamesSec@LCF
Thank you for reaching out to Microsoft Q&A forum and sharing the details and for the thorough troubleshooting.

Based on everything you’ve tested, I would like to share some information from my side that I hope will be helpful in showing that there is no misconfiguration on your end.

What you’re seeing is a known limitation when using Teams with on-premises Exchange mailboxes. You can see detailed information here: Resolve interaction issues between Teams and Exchange Server - Microsoft Teams | Microsoft Learn

When User 1 clicks Teams Meeting while creating an appointment directly on User 2’s calendar, Teams treats User 2 as the meeting organizer. Creating a Teams meeting on a delegated or shared calendar requires the organizer’s mailbox to be hosted in Exchange Online.

User 1 is able to create Teams meetings on their own calendar, but the same action fails when attempted on any other user’s calendar. In those cases, Outlook displays the error message "make sure you’re signed in to Teams" even though Teams sign‑in is already working.

However, I also found this workaround you can consider that User 1 can create the Teams meeting on their own calendar and invites User 2 > User 2 creates the Teams meeting themselves; delegates can edit it afterward > Move the organizer mailbox(s) to Exchange Online, where delegated Teams scheduling is supported.

For your information, here are some articles you can see:

How Exchange and Microsoft Teams interact - Microsoft Teams | Microsoft Learn

Admin - Authentication requirements and functionality of the Teams Meeting add-in in Outlook - Microsoft Teams | Microsoft Learn

I hope these suggestions provide some helpful.

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  2. AI answer

    2026-01-06T21:36:51.1733333+00:00

    The issue you're experiencing with User 1 receiving the message "To schedule a Teams meeting, make sure you're signed in to Teams" despite being signed in can be related to several factors, especially in an environment where both users are on an on-premises Exchange server. Here are some troubleshooting steps you can consider:

    1. Verify Delegate Permissions: Ensure that User 1 has been granted the correct permissions on User 2's calendar. While you mentioned that User 1 has "True Delegate" permissions, double-check that these permissions are correctly set in the Outlook client under File > Account Settings > Delegate Access.
    2. Check Teams Integration: Since both users are using Office 2021 LTSC, ensure that the Teams integration is functioning correctly. Sometimes, the Teams add-in for Outlook may not work as expected if there are issues with the Teams client itself.
    3. Run Teams Meeting Delegation Connectivity Test: Use the Microsoft Remote Connectivity Analyzer tool to run the Teams Meeting Delegation connectivity test. This can help identify if User 1's account meets the requirements to schedule a Teams meeting on behalf of User 2.
    4. Autodiscover Configuration: Ensure that the Autodiscover service is correctly configured for both users. Misconfigurations can lead to issues with Teams and Exchange interactions.
    5. Update Office and Teams: Make sure that both the Teams client and Office applications are up to date. Sometimes, updates can resolve underlying issues with integrations.
    6. Check for Cached Mode Issues: If User 1 is working in Cached mode in Outlook, it may cause conflicts. Try switching to Online mode temporarily to see if that resolves the issue.
    7. Review Third-Party Add-ins: If there are any third-party add-ins installed in Outlook, they may interfere with the Teams add-in. Consider disabling them to see if that resolves the issue.

    If the problem persists after trying these steps, it may be beneficial to consult Microsoft support for further assistance, as they can provide more in-depth troubleshooting based on your specific environment.

    References:

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