Slack api conversations.history returns error: not_in_channel - slack-api

Question

I'm starting out with the Slack API and trying to just get a list of messages.
Here are my steps:
Created a Slack app and gave it channels:read and channels:history scope (also re-installed it)
Queried the list of channels with conversations.list (this worked fine)
From the output of conversations.list, I found a channel that I use and copied the id
Used the conversations.history api with the channelid from step 3
Result:
{ "ok": false, "error": "not_in_channel" }
I'm not at all sure what is happening here. I definitely have messages in the channel, and the documentation page for that api does not say anything about this "not_in_channel" error code.
What am I doing wrong?

Answer 1

After a long time of investigations (~2 hours), I found an easy approach. For Caleb's answer, I didn't understand how to invite a Bot to the channel. Hence, I am posting this answer.
Go to your Slack Channel and type the following as a message.
/invite #BOT_NAME
Eg: If your Bot name is SRE Incident Manager the command would be as follows.
/invite #sre_incident_manager
As soon as you start typing #, Slack will automatically suggest. So it becomes easy. For this, the Bot needs to be added to your Slack Workspace.
PS: Original answer.

Answer 2

The error not_in_channel has the exact meaning, your custom Slack app should be added to the channel.
Exact solution 1
To resolve the error, in the Web Slack interface:
Open channel settings
Click on the Integrations tab
Click Add apps and find your custom app.
Slack app might have different interface, see Iryna Vernik's answer.
Alternative solution 2
Give access to the bot to all channels by adding workspace wide scope, for example, chat:write.public. Depends on your needs and security requirements.
Alternative solution 3
To access the channel chat from API specify Incoming webhook. Slack will generate a unique URL with the token per each channel. Only convenient for a few channels.

Answer 3

This error arises when you are using the bot oauth token and the bot is not invited to the channel. To solve this you need to
Invite the bot(slack app) to join the channel.
Use the OAuth Access Token instead
To add Bot to your channel you need to write /invite #Bot_name in the slack channel

Answer 4

I also didn't understand how to invite a Bot to the channel. Way that was proposed by Caleb and Keet was not clear for me or not working. From my side, 'invite' work after
open channel
in Details tab, choose a 'More'clause
in dropdown menu, chouse an 'add app'
in pop-up look for you app (bot)
Also i was use Bot User OAuth Access Token, because i need this functionality in private channel (additionaly, you should add for bot groups:history scope)

Answer 5

FOr me, instead of invite a user/bot, I invite the app.

Answer 6

I'm getting started with the Slack API as well, and I've come to realize that not_in_channel simply means that the user/bot you are using the token for hasn't joined that particular channel you're trying to perform an action on.
Think of it this way: if you're using Slack on the web-browser or web-app, you wouldn't be able to post a message on a channel you haven't either joined or was invited to.
☝️ You'll also never run into this issue through the Slack UI/UX because you're not even able to access the channels UNTIL you are invited or join it.
Click to see png example of a slack message stating my bot being added to a channel
However, because we're using the API we can essentially skip some steps, and in this case we skipped the step where a user/bot has joined the channel before doing the action we're trying to perform (writing a message, grabbing information, etc).
💪 How to address this
There's probably plenty of ways to do it that I'm not versed in, but if you're just concerned about a specific channel or two without the concern of scaling to x channels I'll list the way that worked for me.
📇 /invite Slash Command
As others have mentioned, putting /invite in the message box lets you use Slack's slash command shortcut to add users. What's important is this way also allows us to invite bots to the channel.
Putting "#" triggers Slack to start auto-suggesting, which is why it then becomes easy to find your bot name in the list.
Click here to see screenshot example of the /invite command with #bot_name_here
Hope this helps answer people's question on why it's happening, and thank you to the original posts that got me out of my initial mess. 🙏

Answer 7

As all others said, you need to join each channel.
The bot can join channel programmatically by using API below:
https://api.slack.com/methods/conversations.join
Don't forget to add permission of conversations.join