Mattermost 11.x Upgrade Error: Hidden Archived Channels

Applies to: Mattermost Server v11.x and later

Symptoms: Server fails to start after upgrading from 10.x to 11.x with configuration error about hidden archived channels

🛑 Problem

Mattermost 11.x removed support for hiding archived channels. If your configuration has this setting enabled from a previous version, the upgrade will fail and the server will not start.

Symptoms

Users experiencing this issue will see the following error in their logs:

Error: failed to load configuration: failed to create store: unable to load on store creation: invalid config: Config.IsValid: Hiding archived channels is no longer supported. Make these channels private and remove members instead.

✅ Solution

To resolve this issue and allow the server to start, choose one of the following options to modify your configuration file.

Option 1: Set Configuration Value to True

Edit your config.json file and set the value to true:

"TeamSettings": {
  "ExperimentalViewArchivedChannels": true
}

Then restart the Mattermost server.

Option 2: Remove Configuration Setting

Edit your config.json file and delete the ExperimentalViewArchivedChannels setting entirely, then restart the Mattermost server.

⚠️ Important: After resolving the startup issue, consider migrating away from hidden archived channels. Make affected channels private and remove members to control access instead.

Config-in-Database Environments

If your Mattermost configuration is stored in the database rather than in config.json, the file-based solutions above do not apply. Because this issue prevents the server from starting, the System Console and mmctl are also unavailable.

✅ Solution: Environment Variable Override

Set the following environment variable before starting the server:

Where to set it depends on how Mattermost is deployed:

• systemd: Add it to your mattermost.environment file.
• Docker / Docker Compose: Add it to the environment: block or .env file.
• Kubernetes (Helm): Add it to envVarMap or extraEnvVars in values.yaml.

Then restart the Mattermost server.

Additional Resources

For more information, see:

GitHub Issue #34084 
Mattermost Forum Announcement