WebSocket 403 errors on /api/v2/floorplan when scaling JMeter threads beyond 50

Voice & Telephony
1

Hey,

I am running load tests for our custom agent desktop integration using JMeter 5.6.2. The goal is to validate the WebRTC softphone performance under high concurrency, specifically focusing on the initial handshake and token retrieval.

When I run the test with 20 concurrent threads, everything works fine. The OAuth token is retrieved via POST /oauth/token, and the WebSocket connection to /api/v2/floorplan is established successfully. However, as soon as I scale up to 50 threads, I start seeing a significant number of 403 Forbidden errors on the WebSocket connection endpoint. The error response body just says “Forbidden”.

Here are the details:

  • Environment: Genesys Cloud EU-West
  • JMeter Version: 5.6.2
  • WebSocket Sampler: Used for the /api/v2/floorplan connection
  • HTTP Request: Used for /oauth/token
  • Thread Count: 50
  • Ramp-Up: 10 seconds
  • Loop Count: 1

I have checked the API rate limits, and we are well within the limits for token requests. The 403 errors happen specifically on the WebSocket upgrade request, not the HTTP POST for the token. The token requests are succeeding, but the subsequent WebSocket connection is failing with 403.

I suspect this might be related to how Genesys Cloud handles concurrent WebSocket connections from the same IP or tenant during load spikes. Has anyone encountered similar issues? Is there a specific header or configuration I am missing in my JMeter WebSocket sampler?

Any help would be appreciated.

2

Ah, this looks like a rate-limiting issue masquerading as an authorization error. While I usually deal with bulk recording exports for legal discovery, the underlying platform behavior for API throttling is consistent across endpoints.

When you scale JMeter threads beyond 50, you are likely hitting the 429 Too Many Requests limit, but JMeter might be misinterpreting the response body or the server is returning a 403 Forbidden because the WebSocket handshake token has expired or is being reused across too many concurrent sessions. In Genesys Cloud, OAuth tokens for WebSocket connections are often short-lived and single-use or limited in concurrency per user context.

Check your JMeter script. Are you using a single OAuth token for all 50+ threads? If so, this will fail. Each thread (or logical agent) needs its own unique OAuth token obtained via POST /oauth/token.

Also, verify the Accept-Language and User-Agent headers. Sometimes, a sudden spike in identical headers from a test tool triggers the Web Application Firewall (WAF), resulting in a 403.

Try adding a small random delay (e.g., 100-300ms) between token requests in your JMeter setup to mimic human-like behavior and avoid triggering the WAF.

Here is a quick check for your token flow:

// Pseudo-code for JMeter JSR223 PreProcessor
def token = vars.get("oauth_token");
// Ensure this token is unique per thread and not shared
log.info("Using token for thread: " + ctx.getThreadNum());

If the issue persists, check the Genesys Cloud Admin dashboard for “API Throttling” logs. You might need to request a temporary limit increase for testing purposes. For legal hold exports, we see similar issues when bulk jobs are triggered too rapidly without proper pagination handling.