Users are experiencing a 422 error when attempting to send test messages to a private Slack channel via the Discourse chat integration. yanokwa reports the error occurs even after reinstalling the Slack app and reconfiguring rules, with logs indicating a channel_not_found error. The issue persists despite proper scopes being configured and the /discourse watch command working in the private channel. david suggests verifying scopes and testing with slash commands, while antulik notes that notifications work for new Slack channels but not for older ones, suggesting a possible issue with channel migration or permissions.
When I try to send a test message to a private (but previously public) channel, I get a 422 error. When I check the logs, I see this:
Test provider failed {:error_key=>"chat_integration.provider.slack.errors.channel_not_found", :request=>"", :response_code=>"200", :response_body=>"{\"ok\":false,\"error\":\"channel_not_found\"}"}
This setup worked when the channel was private. I tried re-installing the Slack app and deleting the rules and recreating them. When I use @username rule or a public channel that seems to work well.
