Errors and recovery

How-to guideApplies to: Unified engine deployments

Read the status and error code together. A failed HTTP exchange does not always prove that a mutation was rejected.

Error body

{
  "error": {
    "code": "revision_conflict",
    "message": "The resource changed; refresh before trying again"
  }
}

Some domain responses add structured validation details. Response examples show the server’s response, including non-JSON proxy errors. Large previews are limited.

Status	Typical meaning	Next action
400	Invalid request or unsupported fields.	Correct the named field or syntax.
403	Access or a configured action is denied.	Check the deployment’s access context.
404	Resource not found.	Check its identity and scope.
405	Method not allowed.	Check the method for that route.
409	Identity conflict, revision conflict, busy resource, or result not ready.	Read the error code and current state.
410	Closed session or expired results.	Use available history; do not assume rows remain.
413	Request or response exceeds a limit.	Reduce payload or page size.
415	Wrong content type.	Send application/json where required.
422	Domain validation failed, including configuration edits.	Inspect validation details.
501	Operation or optional service is unavailable on this instance.	Check capabilities and supported features.
503	Dependency unavailable or outcome unknown.	Preserve request identity and inspect state before retrying.

These are common mappings, not a promise that every endpoint returns every status. A gateway can add its own authentication or transport responses.

Separate request and execution failures

A 202 response can later lead to a failed operation. A 200 status read can report a Failed run. A notification can fail after a successful data workflow. Follow the relevant resource’s state and failure details.

Collect useful evidence

Keep the resolved request URL, method, non-secret input, request identity, resource IDs, revision, HTTP status, error code, and timestamps. Correlate operation, run, task, attempt, and audit data as appropriate. See Request identity before repeating a mutation after a lost response.

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Error body

Separate request and execution failures

Collect useful evidence

​Error body

​Separate request and execution failures

​Collect useful evidence

Error body

Separate request and execution failures

Collect useful evidence