Try enabling the Microsoft Teams channel in your Azure Bot Service and make sure its status shows healthy, confirm the bot’s messaging endpoint is correct and publicly reachable, check the app registration in Entra ID so the Microsoft App ID and secret or certificate are valid and admin consent is granted, verify the Teams app manifest contains the right botId and scopes, look at Bot Framework and Azure diagnostic logs and use the Bot Framework Emulator and the portal’s Open in Teams to reproduce errors, check for network, TLS or CORS issues that could block the endpoint, ensure the bot has the necessary roles and permissions in the target tenant, and if the problem continues gather request IDs, timestamps and example error messages and open a support case or post those details to Microsoft Q&A so the issue can be investigated.