Problem
After upgrading to Mattermost 10.11.6, which includes the pre-packaged MS Teams Meetings plugin version v2.3.0, the MS Teams Meetings integration may stop working. Users may see a 500 error or the plugin may become unresponsive when attempting to start a Microsoft Teams meeting.
Symptoms
- Clicking “Start Teams Meeting” results in an error
- Teams meeting links fail to generate
- The plugin repeatedly restarts or fails health checks
The issue occurs because the updated plugin attempts to read Microsoft Teams tokens that were stored before the upgrade. These older tokens can no longer be decrypted by plugin v2.3.0, causing the plugin to hit a nil pointer condition internally. When this happens, the plugin crashes and stops responding, resulting in the 500 error.
Logs
When this issue occurs, the plugin logs will typically show errors indicating failures while reading or decrypting stored Microsoft tokens. These logs help confirm that the problem is caused by incompatible pre-upgrade data.
{"level":"error","msg":"failed to decrypt stored token","error":"cipher: message authentication failed"}
{"level":"error","msg":"unable to read MS Teams user token","error":"unexpected nil pointer"}
{"level":"error","msg":"plugin crashed while processing request","status":500}
These errors confirm that the plugin is attempting to load tokens encrypted with an older AES key. After regenerating the key, these errors will no longer appear.
Solution
To resolve this issue, the recommended fix is to regenerate the plugin’s AES encryption key. This clears all outdated Microsoft authentication tokens stored before the upgrade, preventing the plugin from trying to read incompatible data that causes the nil pointer crash.
After regenerating the AES key, all users must log in to Microsoft again when starting a Teams meeting. This recreates fresh tokens in the correct format used by the updated plugin. Once users re-authenticate, Teams meeting links will generate successfully and the plugin will operate normally.
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