We are Global Administrators and Teams Administrators, and we recently lost the ability to invite guest users to private or shared channels in Microsoft Teams. We own the team and its associated SharePoint site, and we can still add guests to the team itself. External sharing, B2B access, and the relevant Teams organization policies are enabled. Guests can also be added to folders on the connected SharePoint site, so external sharing appears to be working normally. We were previously able to add guests to both private and shared channels. Could this be caused by a recent Teams change or known issue, or are there additional requirements for adding guests to these channel types?
2 Answers
For private channels, being a Teams or team administrator may not be enough by itself. The person performing the invitation generally needs to be an owner of that specific private channel. Try adding yourself as a channel owner first, then invite the guest from the channel membership settings.
Verify that the user already exists as an external guest in Microsoft Entra ID rather than only being available through SharePoint sharing. After the guest object is present, try starting a one-to-one Teams conversation with that account and then add the user to the channel. This can help complete the guest provisioning process before adding them to a channel.
Also check that the guest is already a member of the parent team or standard channel. A private-channel guest typically needs to belong to the main team before they can be added to the private channel.