run `netstat -vanp tcp | grep 4444` to make sure that this issue is not a port collision
and if something is running on port 4444
run `kill -9 $(lsof -ti tcp:4444)`
At last rerun nightwatch could start selenium server successfully
run `netstat -vanp tcp | grep 4444` to make sure that this issue is not a port collision
and if something is running on port 4444
run `kill -9 $(lsof -ti tcp:4444)`
At last rerun nightwatch could start selenium server successfully