[ERROR] The telnet port 3658 is used by process 20546 instead of target process 27149, you will connect to an unexpected process.
[ERROR] 1. Try to restart arthas-boot, select process 20546, shutdown it first with running the ‘stop‘ command.
[ERROR] 2. Or try to stop the existing arthas instance: java -jar arthas-client.jar 127.0.0.1 3658 -c "stop"
[ERROR] 3. Or try to use different telnet port, for example: java -jar arthas-boot.jar --telnet-port 9998 --http-port -1
原因：上次启动后未正常关闭。
解决方法：按提示进入上次未正常关闭的项目，然后执行shutdown关闭。就可以进入其他项目了
原文：https://www.cnblogs.com/hourukai/p/13625101.html