I am trying to run create-react-native-app on expo app in android.
Firstly ,I created the project by writing command
create-react-native-app t
This error beaus your port it is not open just check port is open or not for ubuntu you can check using the following way
sudo ufw status verbose
check 19000 port open then you need it then run following command if port not open
sudo ufw allow 19000/tcp
for other port runs following command
sudo ufw allow 19001/tcp
because http port not you are getting erro. above step solve your problem similar for mac and windows check firewall setting once