"missing_scope" error occurs when creating event triggers for Slack connections

Japan Knowledge Base
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:white_question_mark: Question
When creating an event trigger from a Slack connection created with Bring Your Own OAuth 2.0 app (BYOA), an “missing_scope” error occurs, preventing the specification of the target channel ID.
Error
missing_scope

:light_bulb: Answer
Cause
The reason is that the necessary OAuth scopes to obtain information about the target channel have not been granted to the Slack App. For obtaining information about private channels, the Slack API scope groups:read is required.
For the BYOA Slack connection, after adding the scopes on the Slack App side, it is necessary to reinstall or reauthorize the Slack App, as well as reconnect the Slack connection on the Integration Service side.

Solution
Please check the following settings.

  1. In the Slack App’s OAuth & Permissions, add the necessary scopes for the target channel type.
    ・Public channels: channels:read
    ・Private channels: groups:read
    ・If sending messages: chat:write

  2. Reinstall or reauthorize the Slack App in the workspace.

  3. In Automation Cloud > Integration Service > Slack Connection, reconnect the target connection.

  4. If the target is a private channel, ensure that the Slack App is added to the target channel.

  5. Create a Slack event trigger in Orchestrator and verify if you can specify the channel ID.

Additional check for Button Clicked trigger

When using the “Button Clicked” trigger with BYOA, please also configure the Interactivity & Shortcuts on the Slack App side. If Slack displays “An error was returned from this app. Please try again later or contact the app developer,” the Request URL of the Slack App may be incorrect.

  1. Copy the Webhook URL from Automation Cloud > Integration Service > Slack Connection > Manage Triggers.

  2. In the Slack App > Interactivity & Shortcuts, set Interactivity to On.

  3. Set the Request URL to the copied Webhook URL from the Integration Service and select Save Changes.

  4. Ensure that the Slack App sending the message with the button is the same as the one used for the BYOA connection.