Deleted Scheduled Messages still sending

Question

I am building a slack application that will schedule a message when someone posts a specific type of workflow in a channel.

It will schedule a message, and if someone from a specific group of users replies before it has sent, it will delete the scheduled message.

Unfortuantely these messages are still sending, even though the list of scheduled messages is empty and the response when deleting the message is a successful one. I am also deleting the message within the 60 second limit that is noted on the API.

Scheduling the message gives me a success response, and if I use the list scheduled messages I get:

[
  {
    id: 'MESSAGE_ID', 
    channel_id: 'CHANNEL_ID',
    post_at: 1620428096, // 2 minutes in the future for testing
    date_created: 1620428026,
    text: 'thread_ts: 1620428024.001300'
  }
]

Canceling the message:

async function cancelScheduledMessage(scheduled_message_id) {
  const response = await slackApi.post("/chat.deleteScheduledMessage", {
    channel: SLACK_CHANNEL,
    scheduled_message_id
  })

  return response.data
}

response.data returns { "ok": true }

If I use the list scheduled message API to retrieve what is scheduled I get an empty array []

However, the message will still send to the thread.

Is there something I am missing? I have the proper scopes set up and the API calls appear to be working.

If it helps, I am using AWS Lambda, and DynamoDB to store/retrieve the thread_ts and message IDs.

Thanks all.

Answer 1

For messages due in 5 minutes or less, chat.deleteScheduleMessage has a bug (as of November 2021) [1]. Although this API call may return OK, the actual message will still be delivered due to the bug.

Note that for messages within 60 seconds, this API does return an proper error code, as described in the documentation [2]. For the range (60 seconds, ~5 minutes), the API call returns OK but fails behind the scenes.

Before this bug is fixed, the only thing one can do is to only delete messages scheduled 5 minutes (the exact threshold may vary, according to Slack) or more (yes not very ideal and may not be feasible for some applications).

[1] Private communication with Slack support.

[2] https://api.slack.com/methods/chat.deleteScheduledMessage