Error occurred while trying to proxy to: localhost:3000/

[sotengboy]

Hi,
I try to run this project on my PC with Ubuntu 18.04, but i got an error like this:
[HPM] Error occurred while trying to proxy request / from localhost:3000 to http://localhost:8081/ (ECONNREFUSED) (https://nodejs.org/api/errors.html#errors_common_system_errors)

I tried to check listen ports with lsof, but i don't see port 8081 on the list. Only port 3000 on the list.

Please Help

Thank You!