The server reports that an async operation failed. The
error_class attribute carries the server-side exception class name (for example, "ValueError" or "DispatcherError"), which is useful for routing in caller code.The server returned 404 for an operation ID. This can mean the server has no record of the operation (after a pod restart, for example) or that the result was TTL-evicted. Resubmit the operation if the work is still needed; the server’s idempotency-key deduplication prevents double-execution.
The server is shutting down (503 response). Retry the request against a different replica.