Does anyone understand why the Predictive Outbound campaign launch endpoint returns 403 Forbidden errors specifically when the JMeter thread count exceeds 15, even though the OAuth token has full permissions?
I am currently validating the API throughput for our predictive routing campaigns using JMeter 5.6.2 running from our Singapore office. The goal is to simulate the API load generated by our internal dashboard when multiple supervisors attempt to adjust campaign parameters simultaneously. I have configured the test plan to target the /api/v2/outbound/campaigns/{campaignId} endpoint with a PUT request to update the progressive_rate and prediction_model fields.
With 10 concurrent threads, the requests complete successfully with 200 OK responses, and the latency remains under 200ms. However, as soon as I increase the thread count to 20 or 30, roughly 40% of the requests fail with a 403 Forbidden status code. The error payload is minimal, just stating “Access Denied,” which makes debugging difficult. I have verified that the OAuth token is valid and has not expired, and it possesses the outbound:campaign:write scope. I also checked the Genesys Cloud admin console, and no specific IP restrictions are blocking the Singapore data center IP range.
I suspect this might be related to rate limiting or a hidden concurrency limit on the predictive outbound API that is not documented in the standard rate limit tables. The documentation mentions general API rate limits, but it is unclear if there are stricter limits for predictive routing endpoints due to the computational complexity of the prediction engine. I have attached the JMeter test plan and the sample response headers. Is there a specific header I should be including to handle this concurrency, or is this a known limitation of the platform API for predictive campaigns? Any insights on how to structure the load test to avoid these 403s while still validating the system’s capacity would be appreciated.