Unable to create Debug Bridge: Unable to start adb server: adb server version (31) doesn't match this client (39); killing...
could not read ok from ADB Server
* failed to start daemon
error: cannot connect to daemon
'C:\download\soft\Android\android-sdk-windows\platform-tools\adb.exe start-server' failed -- run manually if necessary
解决办法：
查找被占用的端口：netstat -aon|findstr "5037"
netstat -aon|findstr "5037"
TCP 127.0.0.1:5037 0.0.0.0:0 LISTENING 1548
TCP 127.0.0.1:5037 127.0.0.1:59769 ESTABLISHED 1548
TCP 127.0.0.1:59769 127.0.0.1:5037 ESTABLISHED 9904
进入1548查看是哪个应用：tasklist|findstr "1548"
找到之后杀死进程，进而解决问题。