development server is not started while scanning the QR code in Expo client application

[San10694]

Description

I recently started to learn React-Native and created a CRNA project.
whenever I scan the QR code in Expo App , the application is not started on my android device though my mobile is connected to same wireless network as my PC (windows)

Expected Behavior

I tried to run "npm start" in command line.code compiled successfully and QR code generated in command line.Whenever I scan this code through Expo app it is not starting my apllication in android device.

Observed Behavior

I got following error

Something went wrong.
could not load exp://192.168.*.**:19000. Network response timed out.
error-log---
uncaught error:java.net.SocketTimeoutException: failed to connect to /192.168.*.**(port 19000) after 10000ms 

Environment

• react-native-scripts:--react-native-scripts@0.0.31
• react-native:-- react-native@0.44.3
• expo:-- expo@17.0.0
• node -v:v6.10.1
• npm -v:3.10.10
• yarn --version:N/A
• watchman version:

1. Operating system:windows-10
2. Phone/emulator/simulator & version:android v 6.0

[danielkcz]

Hey, I am trying very same thing and failing with same error as well. Here are the versions in my case. I am really just starting to know React Native. I haven't done any change there, just clean run of create-react-native-app (no errors during that).

react-native-scripts@0.0.40
react-native@0.45.1
expo@18.0.4
node@6.10.1
npm@3.10.10
yarn@0.24.6

Windows 10 Pro x64
Android 6.0 (LG G3)

Tried disabling Firewall it case it's blocked there, but no luck. I don't have any active antivirus protection.

[danielkcz]

Found a troubleshooting section in readme on this and tried http access. This works and yields this result

// 20170625170940
// http://10.0.75.1:19000/

{
 "sdkVersion": "18.0.0",
 "name": "mapper",
 "slug": "mapper",
 "version": "0.1.0",
 "xde": true,
 "developer": {
 "tool": "crna"
 },
 "packagerOpts": {
 "hostType": "tunnel",
 "lanType": "ip",
 "dev": true,
 "strict": false,
 "minify": false,
 "urlType": "exp",
 "urlRandomness": null
 },
 "env": {
 
 },
 "bundleUrl": "http://10.0.75.1:19001/./node_modules/react-native-scripts/build/bin/crna-entry.bundle?platform=ios&dev=true&strict=false&minify=false&hot=false&assetPlugin=expo/tools/hashAssetFiles",
 "debuggerHost": "10.0.75.1:19001",
 "mainModuleName": "./node_modules/react-native-scripts/build/bin/crna-entry",
 "logUrl": "http://10.0.75.1:19000/logs",
 "id": "@anonymous/mapper-183ba25c-82ec-44fa-835f-05f67178c163"
}

On the same address but 19001 port there is only a message React Native packager is running..

Trying to access same address on the phone doesn't work, it cannot connect. I also tried connecting my computer to a wifi hotspot created on the phone. Same result.

Also noticed the url http://10.0.75.1:19000/logs in the output above, but that doesn't work either (on a computer).

Honestly, I don't think that IP address is a correct one there. I am not sure how is that obtained, but my network runs on regular 192.168.0.XXX addresses. How can my phone find that IP address?

[San10694]

@FredyC I got an alternative for same problem
please download "Expo XDE" (desktop application) it will definately solve your problem.
following steps you need to follow
1-download Expo XDE for your appropriate OS(ie. windows or mac) from https://expo.io/
2-open Expo XDE and you will find your CRNA project , click on specific project you want to run ,,
3- click on the gear icon in address bar and select host as a Lan , here you will find your "ipAddress:host"
paste this address to your expo mobile App in explore section
and if everything is right then you will get your application running on your mobile .....
hope it will help you

[brentvatne]

this might also be useful for you folks: https://github.com/react-community/create-react-native-app/blob/d01ddabb634532200629c6d17f920eb856fa6416/react-native-scripts/template/README.md#environment-variables

[San10694]

thanks @brentvatne,
but unfortunately I got same error after setting enviornment variables. Only solution I got so for is to run my CRNA app in "Expo XDE" as I explained in my above comment .
thanks for the help buddy

[danielkcz]

Ok, I think I've found the culprit. I have a Docker installed which has its own network adapter. For some reason the Expo picks this virtual network over the real one. Using env variable as @brentvatne suggested works, but it's totally cumbersome solution.

I am wondering if this could be somehow configurable per project.

[ide]

@FredyC One thing that might achieve a lot of what you are looking for is to use direnv (https://direnv.net). When you have direnv installed on your computer and set up in your shell profile, it will check for a file called .envrc, which is just a Bash script, in every directory you cd into.

So you could make a file at ~/your-project/.envrc with export REACT_NATIVE_PACKAGER_HOSTNAME=$(hostname) and it would apply only when your terminal is in your project directory (or one of its subdirectories).

[ahmetkakici]

Today i got the same error (Network response timed out.) also couldn't access packager's address from iphone's browser.
The problem was packager gets the first network adapter's local address (for me it was virtual-box adapter) 192.168.56.1 but my wireless network's local address was 192.168.1.28
So instead of scanning url, i manually entered exp://192.168.1.28 to expo ios-app and it worked.

[danielkcz]

Yea, in the end, I've solved the problem by changing priorities of my network adapters so the one I want is a first one. Works like magic :)

[danielkcz]

Anyway, in my opinion, this should be solved on the Expo side to allow to pick which adapter to use. It's not always feasible to switch adapters priorities, in particular for people moving between e.g. wifi and wired connection.

[brentvatne]

@FredyC - I don't know much about network adapter priorities and have never encountered this issue myself -- would you be interested in helping us handle this on the Expo side?

[danielkcz]

@brentvatne Sure thing, just let me know what do you need from me. I am not sure about the way how Expo is finding that IP address. If you have access to a list of adapters of there is some high-level API only.

[GJS153]

I have tried all the suggestions listed above, but none of them worked. Here the error message that I got on my phone: "Uncaught Error: java.net.SocketTimeoutException:connect timed out"
Could someone help me out?

[brentvatne]

@FredyC - it just uses the ip node package -- ip.address() -- https://github.com/expo/xdl/blob/1e3f6637244b112a23963294f71a6a8d2e1b55c8/src/UrlUtils.js#L222

[danielkcz]

@brentvatne Ok, I see. The ip.address() allows specifying the name of the network adapter in a first argument. So if Expo can read that optionally from some config, it could solve all problems.