'Unable to start server' on npm start on create-react-native-app

Description

Created react native app using create-react-native-app and error on when run npm start in the app folder

Expected Behavior

To start the app and show QR code which a mobile can connect through expo app.

Observed Behavior

What actually happened when you performed the above actions?

If there’s an error message, please paste the full terminal output and error message in this code block:

> whyerrors@0.1.0 start /home/pankaja/Documents/Projects/react-native/whyerrors
> react-native-scripts start

5:24:24 PM: Unable to start server
  See https://git.io/v5vcn for more information, either install watchman or run the following snippet:
    sudo sysctl -w fs.inotify.max_user_instances=1024
    sudo sysctl -w fs.inotify.max_user_watches=12288

npm ERR! Linux 4.13.0-25-generic
npm ERR! argv "/usr/bin/node" "/usr/bin/npm" "start"
npm ERR! node v6.11.4
npm ERR! npm  v3.5.2
npm ERR! code ELIFECYCLE
npm ERR! whyerrors@0.1.0 start: `react-native-scripts start`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the whyerrors@0.1.0 start script 'react-native-scripts start'.
npm ERR! Make sure you have the latest version of node.js and npm installed.
npm ERR! If you do, this is most likely a problem with the whyerrors package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR!     react-native-scripts start
npm ERR! You can get information on how to open an issue for this project with:
npm ERR!     npm bugs whyerrors
npm ERR! Or if that isn't available, you can get their info via:
npm ERR!     npm owner ls whyerrors
npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:
npm ERR!     /home/pankaja/Documents/Projects/react-native/whyerrors/npm-debug.log

Environment

Please run these commands in the project folder and fill in their results:

• npm ls react-native-scripts: react-native-scripts@1.8.1
• npm ls react-native: react-native@0.50.3
• npm ls expo: expo@23.0.6
• node -v: v6.11.4
• npm -v: 3.5.2
• yarn --version: not installed
• watchman version: not installed

Also specify:

1. Operating system: Ubuntu 17.10
2. Phone/emulator/simulator & version: not relevant

Reproducible Demo

[kennylbj]

Just type following commands to fix it if you don’t wanna install Watchman

sudo sysctl -w fs.inotify.max_user_instances=1024
sudo sysctl -w fs.inotify.max_user_watches=12288

[redbar0n]

Fixed it.

watchman installation is required:

https://facebook.github.io/watchman/docs/install.html

Thanks to @austinhale suggesting it in this related issue: https://github.com/react-community/create-react-native-app/issues/515