Summary

When entering the Jira server unique ID in Microsoft Teams, the following message appears: 

Please check if ... is valid Jira unique ID and Jira Server for Microsoft Teams app for your organization is installed. 

Cause

This may happen if the Jira unique ID is (or was previously) used for another integration between the Jira instance (or a copy of it in a lower environment). 

Solution

Re-installing the Microsoft Teams for Jira app will generate a brand-new server ID.