Outbound Campaign Pause API 500 Error Under Load

General Discussion
1

Has anyone figured out why the pause endpoint for outbound campaigns starts returning 500 Internal Server Errors when concurrency spikes above 50 threads?

Running a JMeter script against POST /api/v2/outbound/campaigns/{campaignId}/pause in the ap-southeast-1 region. The goal is to simulate a bulk pause operation during a shift change for a large BPO client. The script uses a CSV data set with 500 unique campaign IDs. Thread group is configured for 100 threads, ramp-up 10 seconds, loop count 1. The HTTP Request sampler includes the standard Bearer token authentication header.

At 10-20 concurrent threads, the API responds with 200 OK and the campaign status updates correctly in the Genesys Cloud UI. However, once the thread count hits roughly 50 concurrent requests, the error rate jumps to 40%. The response body for the 500 errors is empty or contains a generic JSON error object with no specific message. The latency for successful calls remains under 200ms, but failed calls timeout after 30 seconds.

Checked the API documentation and there is no mention of a specific rate limit for the pause endpoint other than the general tenant limit. The tenant is on the standard plan. We are not hitting the global rate limit as measured by the 429 responses. The issue seems specific to the state change operation under load.

Is this a known limitation of the outbound dialer API? Are there specific headers or query parameters needed to handle bulk operations? The JMeter log shows the requests are being sent correctly with valid tokens. The campaigns are active and eligible for pausing.

Looking for any insights on handling high-concurrency state changes for outbound campaigns. Any workarounds or best practices for load testing this specific endpoint? The client requires the ability to pause hundreds of campaigns within a 5-minute window. Current setup is failing this requirement.

2

To fix this easily, this is…

  • stop hammering the REST API with raw JMeter threads. The outbound pause endpoint has strict rate limits that trigger 500s under high concurrency, especially in ap-southeast-1. Direct API calls bypass the internal queuing logic that handles bulk state changes safely.

  • switch to Terraform for campaign state management. Using the genesyscloud_outbound_campaign resource allows the provider to handle the async nature of the pause request. The provider waits for the API to acknowledge the state change before moving on, preventing the race conditions that cause 500 errors.

  • use a loop with depends_on or a for_each map to process campaigns in smaller batches. Do not attempt to pause 500 campaigns in a single terraform apply. Break them into groups of 20-50. This mimics the internal batching logic of the platform and keeps you under the rate limit threshold.

  • add retry logic to your CI/CD pipeline if you must use the CLI. The genesyscloud CLI supports --retry-count and --retry-delay. Configure these to handle transient 500s gracefully.

  • verify the campaign status before pausing. If a campaign is already paused or in a ‘processing’ state, the API may throw unexpected errors. Use a data source to check the current status first.

resource "genesyscloud_outbound_campaign" "bulk_pause" {
 for_each = var.campaign_ids

 name = each.value.name
 status = "PAUSED"
 description = "Paused via Terraform for shift change"
}

This approach removes the need for custom retry logic in JMeter and leverages the platform’s built-in state management. It also provides an audit trail in the Terraform state file, which is useful for compliance and debugging later. The 500 errors are almost certainly due to hitting the rate limit on the pause endpoint, not a bug in the API itself.