No data received ERR_EMPTY_RESPONSE webpack

I am trying to run webpack-dev-server, but when I go to `http://localhost:8080/` the browser returns 

```
No data received 
ERR_EMPTY_RESPONSE
```

**Solution**

I was able to resolve this issue by explicitly telling webpack to use port 3000 

```
webpack-dev-server --port 3000
```

go ->  `http://localhost:3000/`

It's not clear why the server didn't run in the defaulted port number? 
