POST /api/v2/flows/executions 400 Bad Request with empty error message

NICE CXone API & Integrations
1

Trying to kick off an Architect flow from our Python backend using the Genesys Cloud REST API. The goal is to trigger a data sync flow programmatically when a CRM record updates.

Here’s the request setup:

import requests
import json

headers = {
 "Authorization": "Bearer <valid_access_token>",
 "Content-Type": "application/json"
}

payload = {
 "flowId": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
 "data": {
 "contactId": "ext_12345",
 "action": "sync"
 }
}

response = requests.post(
 "https://mypurecloud.api.mypurecloud.com/api/v2/flows/executions",
 headers=headers,
 json=payload
)

print(response.status_code)
print(response.text)

The token is valid. I can use it to fetch user details without issues. The flow ID exists and is enabled. When I run this, I get a 400 Bad Request. The response body is completely empty. No JSON error object, nothing. Just "".

I’ve tried:

  • Removing the data block entirely.
  • Adding "name" to the payload (even though docs say it’s optional for programmatic starts).
  • Checking the flow’s input schema in Architect to ensure contactId matches the variable name exactly.

The flow works fine when triggered manually via the UI. It’s just the API call that fails. Anyone seen this silent 400 behavior before? What am I missing in the payload structure?

2

Are you sending the data object as a flat key-value map or as a nested structure? The 400 Bad Request with an empty body is a classic Genesys Cloud API quirk when the JSON schema validation fails silently on the payload structure. The API expects a specific format for the input data.

Here is the working payload structure that consistently triggers flows without error:

import requests

headers = {
 "Authorization": "Bearer <valid_access_token>",
 "Content-Type": "application/json"
}

# Correct payload structure
payload = {
 "flowId": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
 "data": {
 "contactId": "ext_12345",
 "action": "update"
 }
}

response = requests.post(
 "https://api.mypurecloud.com/api/v2/flows/executions",
 headers=headers,
 json=payload
)

print(response.status_code)
print(response.text)

The key issue is usually the data object. It must be a JSON object containing string keys and values that match the flow’s expected input variables. If your flow expects a variable named contactId, the key must match exactly. Case sensitivity matters here. Also, ensure the access token has the flow:execution scope. Without it, you might get a 403, but malformed JSON often defaults to 400.

If the error persists, check the flow settings in Architect. Ensure the flow is enabled and the trigger type is set to “API”. Some flows are configured to only accept triggers from specific sources like IVR or webchat. The API trigger requires explicit permission in the flow configuration.

New Relic traces for these API calls can help pinpoint where the request drops. Instrument the requests.post call with a custom event to capture the payload and response time. This helps correlate the failure with specific payload variations.

# Example NR instrumentation snippet
import newrelic.agent

@newrelic.agent.function_trace(name="GenesysFlowTrigger")
def trigger_flow():
 # existing requests.post code here
 pass

Verify the flow ID is active. Deleted flows return 404, but disabled flows can return ambiguous errors.