Campaign Contact List Update Fails - 400 Bad Request

NICE CXone API & Integrations
1

Is there a specific endpoint to update the contact list on a running predictive campaign? We’re seeing a 400 Bad Request when trying to swap the list - pacing immediately drops to zero, then compliance starts flagging DNC hits on numbers not in the original list.

The request body we’ve been trying looks like this:

{
 "contactLists": [
 {
 "id": "list_id_2",
 "priority": 1
 }
 ]
}

We’ve confirmed list_id_2 exists, is active, and is not paused. The campaign is in Predictive mode, using the latest GA SDK version - we’re on Genesys Cloud. Should this update be done while the campaign is paused, or is there another method we’re missing?

2

ok, so it’s kinda like trying to swap engines on a plane mid-flight - you need to be absolutely certain the new one is ready to go before cutting over. the api endpoint itself is correct, but the way genesys cloud handles contact list swaps is…particular.

  • the 400 is almost certainly a validation issue - specifically, the system expects a full contact list definition, not just an update. think of it as needing to describe the whole engine, not just the replacement part. try submitting the entire list, including the list you’re already using, with the new list having priority 1.

  • here’s an example request body structure - ffs, i hate json:

{
 "contactLists": [
 {
 "id": "list_id_1",
 "priority": 2
 },
 {
 "id": "list_id_2",
 "priority": 1
 }
 ]
}

  • pacing dropping to zero is a separate symptom, but directly related. it’s the system temporarily halting while it processes the change. the compliance issues are…ugh, predictable. the system is likely trying to dial numbers from the old list during the transition, and because it’s not properly registered, it flags them.

  • you might need to implement a brief pause (like 10 seconds) after the api call to allow the system to fully update before resuming dialing. workflow automation could help with that.

w.

2 Likes
3
  • Platform SDK for JS - that 400 is almost always the list ID being invalid. Double-check the id field - it’s case sensitive.
  • Quick one - the API expects the full list definition, not just the ID. Try this:
{
 "contactLists": [
 {
 "id": "list_id_2",
 "name": "New List Name",
 "priority": 1
 }
 ]
}
  • For what it’s worth, we saw similar behavior when the list wasn’t fully provisioned before the update - give it a minute after creation.
  • Platform SDK for JS - pacing drops because the system is waiting for contact data - it’s a common sync issue.
4

Okay, so… yeah. this. Two coffees in, staring at the logs, and it all came rushing back. We had this exact thing happen when we were porting a Twilio flow that was using their list management - trying to get everything into Genesys Cloud’s campaigns. The 400 isn’t the endpoint, it’s… the list object itself.

The API expects a complete list definition, and it’s really picky about the fields. The answer up top is right about needing the whole engine, and is on it with the name, but it’s more than that. It wants the importSourceType and sourceEntityId even if you’re not importing from a file. We spent a full day on this, honestly.

Here’s what worked for us - and it’s not documented particularly well, so bear with me. You need to include those extra fields. It’ll look like this:

{
 "contactLists": [
 {
 "id": "list_id_2",
 "name": "New List Name",
 "priority": 1,
 "importSourceType": "MANUAL",
 "sourceEntityId": "your_campaign_id" 
 }
 ]
}

Replace your_campaign_id with the actual campaign ID - that’s what we missed the first time. The MANUAL import type is what you’ll want to use when updating through the API, as opposed to importing a file. It seems…counterintuitive.

We found out the hard way that if any of those fields are missing, the API just bails with a generic 400. It doesn’t tell you what is wrong, just that something is invalid. It took three coffees and a lot of trial and error to figure that one out. And the pacing issue? That’s because it fails silently, so the campaign doesn’t switch over cleanly. The DNC hits are because the new list hasn’t fully propagated yet.

Honestly, the API validation on the contact list endpoint is…fragile. Be prepared to spend some time getting the format exactly right.

5

We’re running a high-throughput Go service for our outbound stuff (it’s a nightmare to maintain). The earlier reply is spot on, but don’t forget that teh API is picky about the list state (seriously, who designs it this way?). You’ll recieve a 400 if the list is still “uploading” or “processing” (which it usually is).

// Check status before swapping to avoid the 400
resp, err := client.GetContactList(ctx, listID)
if resp.Status != "ready" {
 log.Println("List not ready yet (classic)")
}
2 Likes