{"record":{"id":"1cdde3143dea1001","repo":"apache/rocketmq","slug":"consumergroup-can-not-equal-default-consumer-grou-1cdde3","errorCode":null,"errorMessage":"consumerGroup can not equal {DEFAULT_CONSUMER_GROUP}, please specify another one.","messagePattern":"consumerGroup can not equal (.+?), please specify another one\\.","errorType":"validation","errorClass":"MQClientException","httpStatus":null,"severity":"error","filePath":"client/src/main/java/org/apache/rocketmq/client/impl/consumer/DefaultMQPushConsumerImpl.java","lineNumber":1036,"sourceCode":"        } catch (Exception e) {\n            log.warn(\"Start the consumer {} fail.\", this.defaultMQPushConsumer.getConsumerGroup(), e);\n            shutdown();\n            throw e;\n        }\n    }\n\n    private void checkConfig() throws MQClientException {\n        Validators.checkGroup(this.defaultMQPushConsumer.getConsumerGroup());\n\n        if (null == this.defaultMQPushConsumer.getConsumerGroup()) {\n            throw new MQClientException(\n                \"consumerGroup is null\"\n                    + FAQUrl.suggestTodo(FAQUrl.CLIENT_PARAMETER_CHECK_URL),\n                null);\n        }\n\n        if (this.defaultMQPushConsumer.getConsumerGroup().equals(MixAll.DEFAULT_CONSUMER_GROUP)) {\n            throw new MQClientException(\n                \"consumerGroup can not equal \"\n                    + MixAll.DEFAULT_CONSUMER_GROUP\n                    + \", please specify another one.\"\n                    + FAQUrl.suggestTodo(FAQUrl.CLIENT_PARAMETER_CHECK_URL),\n                null);\n        }\n\n        if (null == this.defaultMQPushConsumer.getMessageModel()) {\n            throw new MQClientException(\n                \"messageModel is null\"\n                    + FAQUrl.suggestTodo(FAQUrl.CLIENT_PARAMETER_CHECK_URL),\n                null);\n        }\n\n        if (null == this.defaultMQPushConsumer.getConsumeFromWhere()) {\n            throw new MQClientException(\n                \"consumeFromWhere is null\"\n                    + FAQUrl.suggestTodo(FAQUrl.CLIENT_PARAMETER_CHECK_URL),","sourceCodeStart":1018,"sourceCodeEnd":1054,"githubUrl":"https://github.com/apache/rocketmq/blob/293f5885719fc4aa3619446a1900f58ccfcfdd29/client/src/main/java/org/apache/rocketmq/client/impl/consumer/DefaultMQPushConsumerImpl.java#L1018-L1054","documentation":"checkConfig() rejects the reserved default consumer group name (MixAll.DEFAULT_CONSUMER_GROUP, historically \"default-consumer-group\"/\"default_consumer_group\"-style sentinel). Using it would silently group unrelated consumers together, so the client refuses it.","triggerScenarios":"Passing the literal default group constant as your group name; a config default falling through so code ends up using the sentinel value; copying example code that used the placeholder name.","commonSituations":"Templates or quick-start samples that ship the default group; configuration defaults like consumerGroup: ${mq.group:default_consumer_group} where the real value is never set.","solutions":["Choose a unique, application-specific group name (e.g. appname-consumer-group)","Remove the default value from config placeholders so a missing property fails loudly instead of falling back to the reserved name","Document per-service group naming conventions to prevent collisions"],"exampleFix":"// before\nDefaultMQPushConsumer c = new DefaultMQPushConsumer(MixAll.DEFAULT_CONSUMER_GROUP);\n\n// after\nDefaultMQPushConsumer c = new DefaultMQPushConsumer(\"payment-service-group\");","handlingStrategy":"validation","validationCode":"if (MixAll.DEFAULT_CONSUMER_GROUP.equals(group) || group == null || group.trim().isEmpty())\n    throw new IllegalArgumentException(\"Invalid consumer group: \" + group);","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Use a per-application group naming convention (e.g. <service>-<topic>-cg)","Do not ship config defaults that fall back to the reserved group name","Add a config lint rule rejecting 'default' style group names"],"tags":["rocketmq","config","consumer-group","reserved-name"],"backgroundTag":null,"analyzedSha":"293f5885719fc4aa3619446a1900f58ccfcfdd29","analyzedAt":"2026-08-14T11:50:13.822Z","schemaVersion":2},"datasetVersion":"2026-08-15T17:31:12.345Z"}