SlackBridge "onMessage Error: Not enough permission" since v3.15.0

Description:

After upgrading from v3.14.4 to v3.15.0, SlackBridge stopped working (at least when sending from Slack to Rocket.Chat).

I tried to rollback to 3.14.4 by changing the tag in docker-compose.yml and rebuilding the containers but Rocket.Chat throws Can’t find migration version 225 which I guess is not surprising since mongodb’s structure/schema must have change between 3.14 and 3.15.

If we restore a mongodump backup from before the upgrade we are going to lose a few days of data which is not a good solution.

Steps to reproduce:

Post a message in a Slack channel that is paired with a Rocket.Chat channel (which used to work before 3.15.0)

Expected behavior:

Message is posted in Rocket.Chat

Actual behavior:

No message is posted from Slack to Rocket.Chat, instead the following error is logged:

server.js:204 SlackBridge ➔ Slack.error Unhandled error onMessage Error: Not enough permission
at validateMessage (app/lib/server/functions/sendMessage.js:151:10)
at sendMessage (app/lib/server/functions/sendMessage.js:165:2)
at RocketAdapter.createAndSaveMessage (app/slackbridge/server/RocketAdapter.js:499:5)
at SlackAdapter.processNewMessage (app/slackbridge/server/SlackAdapter.js:830:17)
at SlackAdapter.onMessage (app/slackbridge/server/SlackAdapter.js:453:9)
at app/slackbridge/server/SlackAdapter.js:108:11
at runWithEnvironment (packages/meteor.js:1286:24)

On the other hand sending a message from Rocket.Chat to Slack still works fine, as it did in 13.4.4

Server Setup Information:

• Version of Rocket.Chat Server: 3.15.0
• Operating System: Debian
• Deployment Method: Docker
• Number of Running Instances: 1
• DB Replicaset Oplog: enabled
• NodeJS Version: v12.22.1
• MongoDB Version: 4.0.24 / mmapv1 (oplog Enabled)
• Proxy: traefik
• Firewalls involved: iptables managed by Docker

Start with app/slackbridge/server/SlackAdapter.js and RocketAdapter.js, then trace the reported call through app/lib/server/functions/sendMessage.js, especially validateMessage. Reproduce by posting in a paired Slack channel on Rocket.Chat 3.15.0 and compare the permission failure with the expected successful message delivery.