5.1 版本controller 无法自动切换： org.apache.rocketmq.client.exception.MQBrokerException: CODE: 2012 DESC: The broker has not master, and this new registered broker can't not be elected as master

[PAYNE1Z]

使用 namesrv 内嵌方式部署了controller 4个节点
两个 broker-a 节点 master+slave

当master down机时，slave无法切换到master, 日志中报错

ERROR ReplicasManager_ScheduledService_2 - Failed to register broker to controller
org.apache.rocketmq.client.exception.MQBrokerException: CODE: 2012 DESC: The broker has not master, and this new registered broker can't not be elected as master
For more information, please visit the url, https://rocketmq.apache.org/docs/bestPractice/06FAQ
at org.apache.rocketmq.broker.out.BrokerOuterAPI.registerBrokerToController(BrokerOuterAPI.java:1183)
at org.apache.rocketmq.broker.controller.ReplicasManager.registerBrokerToController(ReplicasManager.java:302)
at org.apache.rocketmq.broker.controller.ReplicasManager.lambda$schedulingSyncBrokerMetadata$4(ReplicasManager.java:353)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:750)

[mxsm]

能提供一下Controller相关的日志吗？

[PAYNE1Z]

（1）下线主备Broker
（2）利用cleanBrokerData命令清除Controller中该组Broker元数据
（3）删除主备Broker下的文件～/store/epochFileCheckpoint和epochFileCheckpoint.bak
（4）Broker重新上线（尽量保证旧的主备关系，先主后备上线）

参考 #6354 这个操作恢复了
可能是因为我更改过 epochFileCheckpoint 目录

[mxsm]

epochFileCheckpoint 这个目录不能改，如果你改动了需要将之前目录中的数据文件也一并移动过去。