This post explains how to fix the “errorCodeTeamsDisabledForTenantForbidden” error when trying to add guest users to Microsoft Teams channel. This issue might arise when a user is invited to a channel in your organization’s Microsoft Teams for the first time. Fixing it usually just requires a flip of a switch, but might also include some waiting.
You get an error screen like this, when trying to join a Teams channel as a guest user.
No fear, though – likely an easy fix!