{"record":{"id":"d7f7b05097008466","repo":"alibaba/canal","slug":"something-goes-wrong-with-reason-ack-geterrorme","errorCode":null,"errorMessage":"something goes wrong with reason: ${ack.getErrorMessage()}","messagePattern":"something goes wrong with reason: (.+?)","errorType":"exception","errorClass":"CanalClientException","httpStatus":null,"severity":"error","filePath":"connector/core/src/main/java/com/alibaba/otter/canal/connector/core/util/CanalMessageSerializerUtil.java","lineNumber":120,"sourceCode":"                        }\n\n                        CanalPacket.Messages messages = CanalPacket.Messages.parseFrom(p.getBody());\n                        Message result = new Message(messages.getBatchId());\n                        if (lazyParseEntry) {\n                            // byteString\n                            result.setRawEntries(messages.getMessagesList());\n                            result.setRaw(true);\n                        } else {\n                            for (ByteString byteString : messages.getMessagesList()) {\n                                result.addEntry(CanalEntry.Entry.parseFrom(byteString));\n                            }\n                            result.setRaw(false);\n                        }\n                        return result;\n                    }\n                    case ACK: {\n                        CanalPacket.Ack ack = CanalPacket.Ack.parseFrom(p.getBody());\n                        throw new CanalClientException(\"something goes wrong with reason: \" + ack.getErrorMessage());\n                    }\n                    default: {\n                        throw new CanalClientException(\"unexpected packet type: \" + p.getType());\n                    }\n                }\n            }\n        } catch (Exception e) {\n            throw new CanalClientException(\"deserializer failed by \" + e.getMessage(), e);\n        }\n    }\n}\n","sourceCodeStart":102,"sourceCodeEnd":132,"githubUrl":"https://github.com/alibaba/canal/blob/87be50e87686a3e8af08c368d0e1ffd1f59eb04a/connector/core/src/main/java/com/alibaba/otter/canal/connector/core/util/CanalMessageSerializerUtil.java#L102-L132","documentation":"Thrown by CanalMessageSerializerUtil.deserializer when the parsed CanalPacket.Packet has type ACK rather than MESSAGES. An ACK packet carries a server-side error/ack reason; deserializer converts it into a CanalClientException whose message is 'something goes wrong with reason: <ack.getErrorMessage()>'. This signals the canal server (or a peer) reported an error/exception for the batch rather than returning data. (This exception is then re-wrapped by the outer catch into 'deserializer failed by ...'.)","triggerScenarios":"A client receives an ACK packet — e.g. a batchId ack/error from the canal server, a subscription/permission error, or an empty/error response — and feeds those bytes into deserializer expecting a data MESSAGES packet.","commonSituations":"Routing server-control/error ACK bytes through the data deserializer instead of the ack-handling path; server-side filter/permission failure causing an error ACK; protocol misuse where the caller does not switch on packet type before deserializing.","solutions":["Inspect the ack.getErrorMessage() text (surfaced in the exception message) to obtain the server-side reason and address that root cause.","Switch on PacketType before calling the MESSAGES deserializer; handle ACK packets via the dedicated ack path rather than deserializer().","Verify subscription/filter/permissions on the canal server if the ACK reason indicates an auth or filter error."],"exampleFix":"// before\nMessage m = CanalMessageSerializerUtil.deserializer(bytes, lazy);  // bytes are an ACK\n// after\nCanalPacket.Packet p = CanalPacket.Packet.parseFrom(bytes);\nif (p.getType() == PacketType.ACK) {\n    throw new CanalClientException(\"server ack: \"\n        + CanalPacket.Ack.parseFrom(p.getBody()).getErrorMessage());\n}\nMessage m = CanalMessageSerializerUtil.deserializer(bytes, lazy);","handlingStrategy":"try-catch","validationCode":"// Switch on packet type and route ACKs away from the data deserializer\nCanalPacket.Packet p = CanalPacket.Packet.parseFrom(data);\nswitch (p.getType()) {\n    case MESSAGES:\n        // safe to deserialize as Message\n        break;\n    case ACK:\n        CanalPacket.Ack ack = CanalPacket.Ack.parseFrom(p.getBody());\n        throw new CanalClientException(\"server ack error: \" + ack.getErrorMessage());\n    default:\n        throw new CanalClientException(\"unexpected packet type: \" + p.getType());\n}","typeGuard":"boolean isMessagesPacket(byte[] data) throws com.google.protobuf.InvalidProtocolBufferException {\n    return CanalPacket.Packet.parseFrom(data).getType()\n        == CanalPacket.PacketType.MESSAGES;\n}","tryCatchPattern":"try {\n    Message m = CanalMessageSerializerUtil.deserializer(data, lazyParse);\n} catch (CanalClientException e) {\n    if (e.getMessage().contains(\"something goes wrong with reason\")) {\n        String serverReason = e.getMessage();\n        // address the server-side cause; do not treat as a parse bug\n        log.error(\"canal server ACK error: {}\", serverReason);\n    } else throw e;\n}","preventionTips":["Switch on PacketType before choosing the data-deserialize path.","Surface ack.getErrorMessage() to operators so server-side errors are visible.","Verify subscription/filter/permissions when ACKs carry auth or filter errors."],"tags":["serialization","protocol","server-error","deserialization"],"backgroundTag":null,"analyzedSha":"87be50e87686a3e8af08c368d0e1ffd1f59eb04a","analyzedAt":"2026-08-14T04:30:11.918Z","schemaVersion":2},"datasetVersion":"2026-08-14T05:17:29.042Z"}