Description:

Slack import fail unexpectedly in both Docker developer version and Docker latest version with generic error message displayed in chat client letting user know import has failed, but no console error in browser and no active error response from server (only an import.js error on server start in both Docker developer and latest, not on Slack import attempt).

Steps to reproduce:

1. Go to Administration > Import > Slack Import > Start Importing
2. Attempt to upload .zip file containing raw backup of Slack channels via latest Slack export template.
3. Import is read successfully by client, with options to select/deselect channels/users.
4. Import is run, but fails only a handful of entries in (~20 - 40 entries in) with generic error message, "An error occurred while running the import."

Expected behavior:

The import would be successful, or at least output an error in the browser console or the server.

Actual behavior:

No error, save for a persistent server error regarding import.js (see error doc below)

Server Setup Information:

• Version of Rocket.Chat Server: both developer and latest images on Docker (1.0.0-develop / Apps Engine Version 1.4.0)
• Operating System: Ubuntu Server 18.04 (4.18.0-15-generic)
• Deployment Method: Docker
• Number of Running Instances: 1
• NodeJS Version: v8.11.4
• MongoDB Version: Latest

Additional context

Happens in both browser and client

Relevant logs:

Console log from browser:

No visible error in browser console.

Log from server, which is my only lead so far:

Rocketchat:logger server.js:199 Slack Importer ➔ error TypeError: Cannot read property 'forEach' of null at message.reactions.forEach.reaction (packages/rocketchat:importer-slack/server/importer.js:299:26) at Array.forEach () at msgs.messages.forEach.message (packages/rocketchat:importer-slack/server/importer.js:295:28) at Array.forEach () at Object.keys.forEach.date (packages/rocketchat:importer-slack/server/importer.js:284:22) at Array.forEach () at DDPCommon.MethodInvocation.Meteor.runAsUser (packages/rocketchat:importer-slack/server/importer.js:282:32) at packages/dispatch_run-as-user.js:211:14 at Meteor.EnvironmentVariable.EVp.withValue (packages/meteor.js:1304:12) at Object.Meteor.runAsUser (packages/dispatch_run-as-user.js:210:33) at Object.keys.forEach.channel (packages/rocketchat:importer-slack/server/importer.js:278:13) at Array.forEach () at Meteor.defer (packages/rocketchat:importer-slack/server/importer.js:275:32) at Meteor.EnvironmentVariable.EVp.withValue (packages/meteor.js:1304:12) at packages/meteor.js:620:25 at runWithEnvironment (packages/meteor.js:1356:24)