{"record":{"id":"81dce6ae1cf61296","repo":"apache/seatunnel","slug":"open-scanner-result-from-is-null","errorCode":null,"errorMessage":"Open scanner result from {} is null.","messagePattern":"Open scanner result from (.+?) is null\\.","errorType":"console","errorClass":null,"httpStatus":null,"severity":"error","filePath":"seatunnel-connectors-v2/connector-doris/src/main/java/org/apache/seatunnel/connectors/doris/backend/BackendClient.java","lineNumber":140,"sourceCode":"    /**\n     * Open a scanner for reading Doris data.\n     *\n     * @param openParams thrift struct to required by request\n     * @return scan open result\n     * @throws DorisConnectorException throw if cannot connect to Doris BE\n     */\n    public TScanOpenResult openScanner(TScanOpenParams openParams) {\n        log.debug(\"OpenScanner to '{}', parameter is '{}'.\", routing, openParams);\n        if (!isConnected) {\n            open();\n        }\n        TException ex = null;\n        for (int attempt = 0; attempt < retries; ++attempt) {\n            log.debug(\"Attempt {} to openScanner {}.\", attempt, routing);\n            try {\n                TScanOpenResult result = client.openScanner(openParams);\n                if (result == null) {\n                    log.warn(\"Open scanner result from {} is null.\", routing);\n                    continue;\n                }\n                if (!TStatusCode.OK.equals(result.getStatus().getStatusCode())) {\n                    log.warn(\n                            \"The status of open scanner result from {} is '{}', error message is: {}.\",\n                            routing,\n                            result.getStatus().getStatusCode(),\n                            result.getStatus().getErrorMsgs());\n                    continue;\n                }\n                return result;\n            } catch (TException e) {\n                log.warn(\"Open scanner from {} failed.\", routing, e);\n                ex = e;\n            }\n        }\n        log.error(ErrorMessages.CONNECT_FAILED_MESSAGE, routing);\n        //        throw new ConnectedFailedException(routing.toString(), ex);","sourceCodeStart":122,"sourceCodeEnd":158,"githubUrl":"https://github.com/apache/seatunnel/blob/cf67b549a7a6c35fa0beb12d83c62892427ea919/seatunnel-connectors-v2/connector-doris/src/main/java/org/apache/seatunnel/connectors/doris/backend/BackendClient.java#L122-L158","documentation":"BackendClient.openScanner sends TScanOpenParams to the Doris BE and expects a TScanOpenResult. When the RPC returns null after all retries it logs this warning each attempt; ultimately openScanner throws DorisConnectorException (following the logged CONNECT_FAILED_MESSAGE error). A null result means the Thrift call completed without exception but yielded no payload, an unexpected BE response.","triggerScenarios":"client.openScanner(openParams) returns null on every retry attempt in the loop — typically a BE-side fault returning an empty response, or an incompatibility between the connector's Doris thrift protocol version and the BE version.","commonSituations":"Doris BE version older/newer than the connector expects; BE overloaded or restarting mid-query; corrupted tablet causing BE to return malformed/empty responses; protocol mismatch after Doris upgrade.","solutions":["Check Doris BE logs (be.INFO/be.out) for errors at the corresponding time.","Confirm connector and Doris versions are compatible; upgrade the connector if BE was upgraded.","Retry the job — transient BE restarts often resolve themselves.","Reduce tablet/batch size to lower BE load if errors correlate with load.","If persistent, validate tablet health (ADMIN SHOW REPLICA STATUS) and repair bad replicas."],"exampleFix":null,"handlingStrategy":"retry","validationCode":"// verify BE health and version before reading\n// SHOW BACKENDS; -- Alive=true, HealthyNum matches\n// check be.INFO for errors around job start","typeGuard":null,"tryCatchPattern":"try {\n    scanner.open();\n} catch (DorisConnectorException e) {\n    // openScanner exhausted retries; inspect BE logs, confirm protocol compatibility, then retry with backoff\n}","preventionTips":["Keep the connector's Doris thrift client version aligned with the cluster version.","Reduce query concurrency/load to avoid BE-side failures.","Validate tablet health (ADMIN SHOW REPLICA STATUS) before large scans.","Retry transient failures; check for BE restarts correlated with the error time."],"tags":["thrift","doris","rpc","null-response"],"backgroundTag":"unexpected-api-response-shape","analyzedSha":"cf67b549a7a6c35fa0beb12d83c62892427ea919","analyzedAt":"2026-09-10T21:44:55.265Z","contentChangedAt":"2026-09-10T21:44:55.265Z","schemaVersion":2},"datasetVersion":"2026-09-14T11:17:12.474Z"}