Important Changes

Significant platform changes that may affect your integration.

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2026-05-19

New HTTP status code for integration setup errors

Integration setup errors now return HTTP status code 409 instead of 503

From Tuesday, May 19, 2026, the following Kombo error codes will start returning HTTP 409 Conflict instead of HTTP 503 Service Unavailable:

Error code	Meaning
INTEGRATION.SETUP_INCOMPLETE	The integration setup hasn’t been finished yet.
INTEGRATION.SETUP_SYNC_PENDING	The initial sync after connection is still running.
INTEGRATION.QA_FAILED	The integration’s setup data didn’t pass our quality checks.

We’re making these changes in accordance with our error handling best practices that we announced with the release of structured error codes in August 2025:

Error handling logic on top of the Kombo API should, if available, always make use of the error.code field in the response, and only fall back to the HTTP status code if the error.code is not present (which should rarely happen).

We’re changing these specific codes because 409 Conflict (RFC 7231) matches the actual error state better. The error.code values themselves are not changing.

What you should do

Start by checking whether your implementation currently branches on the HTTP status code (503 specifically, or 5xx in general) when handling any of the three error codes above.

• If it doesn’t, you’re all set and don’t need to take any action.
• If it does, please update that logic to rely on the error.code field instead of the HTTP status code, so it keeps behaving correctly once these errors start returning 409.

While you’re at it, you may want to consider adding explicit handling for INTEGRATION.SETUP_INCOMPLETE, INTEGRATION.SETUP_SYNC_PENDING, and INTEGRATION.QA_FAILED if you don’t have it yet:

• INTEGRATION.SETUP_INCOMPLETE and INTEGRATION.QA_FAILED should be surfaced to the affected end-customer or admin user because they usually require manual intervention.
• INTEGRATION.SETUP_SYNC_PENDING resolves once the initial sync finishes, but initial syncs can take hours in some cases. We recommend relying on webhooks instead of retrying silently or polling aggressively.

Note that we’ve intentionally chosen a relatively short migration window for this change, as these specific codes are returned infrequently in practice and an unhandled status code switch is unlikely to cause meaningful breakage.

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2026-03-20

Concurrency limiting enforced

Action concurrency limiting is now enforced

Kombo now enforces concurrency limits on action endpoints. Previously, concurrent requests were measured but not rejected. Now, when more than 30 action requests are in flight simultaneously for a single integration, additional requests are rejected with HTTP 429 and the error code PLATFORM.CONCURRENCY_LIMIT_EXCEEDED.

Who is affected: Customers sending many parallel action requests (e.g., bulk-creating candidates or moving applications) may start receiving 429 responses they were not receiving before. Model read endpoints are not affected (e.g. GET /ats/candidates)

What to do:

• Handle the new PLATFORM.CONCURRENCY_LIMIT_EXCEEDED error code in your retry logic.
• Use exponential backoff starting at ~1s.
• Optionally, check the Concurrency-Remaining response header to throttle proactively.

See the full Concurrency Limiting guide for details.