I have just updated Expo to version 5.3.0, and now I am getting this error:
"Error loading DevTools, No scheme specified for development client"
The error appears on a black screen in the browser instead of the expected devtools. The same thing happens when I run either "yarn start" or "npm start".
I have tried reinstalling Expo again, and reinitiating my project again.
So what is the scheme? And how do I include it in my project?
I noticed that in the command line I was also getting this error: "Linking is disabled because the client scheme cannot be resolved". I did a search and found a solution on GitHub: https://github.com/expo/expo-cli/issues/4140.
Solution:
npx uri-scheme
And then
npx uri-scheme add project-name
Try running "expo start" instead.
yarn start or npm start maybe running expo start --dev-client
change it to expo start in
package.json
I have been working with react-native project in another pc and it has been working correctly. Now I cloned project to another device where I have react-native installed since I work with other project and I cannot run it.
When I run react-native run-android I get this error:
Cannot run program "npx": error=2, No such file or directory
I'm using Android Studio 4 on Mac OS Catalina 10.15.6.
I solved the problem by running Android Studio with bellow command on console.
$ open -a "Android Studio.app"
Simple steps you need to go through to make it work with npx
sudo npm uninstall -g react-native-cli
sudo npm i -g npx
npx react-native run-android
More detailed explanation why this is happenig
Issue was that Facebook is not using anymore react-native-cli as they are using npx.
As stated in Facebook page:
If you previously installed a global react-native-cli package, please remove it as it may cause unexpected issues.
So i had to run sudo npm uninstall -g react-native-cli to remove react-native-cli
They also say that npx is shipped with nodejs but that wasn't my case.
React Native has a built-in command line interface, which you can use to generate a new project. You can access it without installing anything globally using npx, which ships with Node.js.
So I had to install it using sudo npm i -g npx
After installing npx then just need to run npx react-native run-android.
Be aware of npx before react-native run-android
Now you don't have any command react-native now we only have 'npx' and react-native run-android is just a parameter for npx. For ex. to start metro we should run npx react-native start
I had the same issues, so I followed these steps:
Start by installing the latest version of Android Studio (Don't delete the old version, just copy paste that to another directory or in my case I just added the Android Studio 3.2.1 that I had to a folder called olderAndroidStudio, on mac).
Make sure you don't click on import settings from Existing.
Follow along the installation, and complete it.
Build and Run, app runs without any problems.
I additionally uninstalled react-native-cli using the method given in the accepted answer.
In my case, I just quit Android Studio and reopened, and the error was gone.
Maybe throw in a ./gradlew clean for goo measure.
I solved it by finding the command that was throwing error and ran it directly
node -e "console.log(require('react-native/cli').bin)"
which outputs a path, something like
$HOME/my-app/node_modules/#react-native-community/cli/build/bin.js
then I pasted that path in android/app/build.gradle
project.ext.react = [
entryFile: "index.js",
enableHermes: true, // clean and rebuild if changing
cliPath: "$HOME/my-app/node_modules/#react-native-community/cli/build/bin.js" // <--- add this
]
Is there any way to open react native app and simulator using one command..
i mean some thing like : react-native run-android --emulator 'PIXEL_API_27'
i also try :
"scripts": {
"start": "node node_modules/react-native/local-cli/cli.js start",
"android": "react-native run-android --emulator 'PIXEL_API_27'",
"test": "jest"
},
and run command npm run android but its complaining that error: unknown option--simulator'`
i am very new with react native. pls help me ....
There is currently no way to open a terminal by passing additional flags to react-native run-android.
So your problem is two fold. First how to run the emulator from the command line, and second how to chain that command with running your react-native project. Let's deal with them in that order.
Opening the emulator from the command line
It is possible to open an emulator via the command line. that is done with the emulator #avd command, replacing #avd with the name of your android virtual device. For example:
emulator #Nexus_5X_API_27_x86
To get the names of the installed android virtual devices on your machine run emulator -list-avds.
Now that your emulator is running let's get react-native running too.
Running the emulator and then running react-native run-android
I have found one issue with running the emulator from the command line, the emulator command keeps executing meaning that you cannot chain commands using &&. However you can run the emulator terminal in the background, by using & so we can chain the commands in the following way:
emulator #Nexus_5X_API_27_x86 & react-native run-android
If you are happy running the terminal in the background, this could be the solution for you.
For more settings for running the emulator from the command line see the docs
Be warned you may get errors when you try to run the emulator command. The most common that I have come across is the PANIC: Missing emulator engine program for 'x86' CPUS. This may require you to dive into your .bashrc or your .bash_profile to get the emulator command to behave. You can see more here
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Getting the following message when I init a new project and then launch the Xcode emulator:
React-Native Version Mismatch
Javascript Version 0.50.1
Native version: 0.50.0
Make sure you have rebuilt the native code. ...
Does anyone know what is going on here and can help me?
This is what I've done with it:
Close all terminals and run build again.
You may forget to close nodejs terminal from another project, and they happen to have installed different react version.
So the code fetches from nodejs server conflicts with the native one.
In case you created your react-native app using create-react-native-app. You should have a app.json (expo). and a package.json file, check if the expo versions match and change accordingly. For example in my case the problem was that in the app.json file I had a 25.0.0 version for the expo sdkVersion attribute, I change that to 23.0.0 and everything worked.
package.json:
"dependencies": {
"expo": "^23.0.4",
"react": "16.0.0",
"react-native": "^0.50.4"
}
app.json:
{
"expo": {
"sdkVersion": "23.0.0" // before was 25.0.0
}
}
Just go to your android/app/build.gradle and then add to the dependencies section:
dependencies{
compile ("com.facebook.react:react-native:0.50.3") { force = true }
}
/// the react native version can be found in package.json
For Android developers who couldn't get it fixed by just closing and rebuilding, Manually uninstall the app on the emulator/device.
just force react native version in your android's app level gradle file, in the dependencies section.
compile ("com.facebook.react:react-native:0.52.0") { force = true }
worked for me
If you're running your React Native app through Expo, upgrading React Native is liable to cause this error (as noted at https://github.com/expo/expo/issues/923).
If that's your scenario, your options are:
Bump Expo (which is listed in your package.json) to a version that is compatible with your React Native version (if one exists, which may not be the case - judging by the linked issue, I figure that Expo support trails React Native releases).
Discard your changes, delete and reinstall your Node modules, Eject from Expo, and then (after checking that you can still run your app post-ejection) try your upgrade again.
I've never seen this error before, but whenever I can't get Xcode and React-Native to play well together, I do a couple of things. Check what version of Xcode I'm working with. If it needs to be updated, I update it. Then clearing watchman and the cache are the second place I go. I don't use the reset cache command. It always says that I need to verify the cache, so I skip that (you can do it though, I just get confused). I use rm -rf $TMPDIR/react-* to get rid of any cached builds. If that doesn't work, I try to build the app in Xcode, then work my way from there, to build it with react-native run-ios. With this error message, it seems you might start by trying to build it with Xcode. Hope that helps...let me know your progress with it. Good luck! (Also, you could update to RN 0.51 as another attempt to get your versions synced.)
I had this problem for the longest time and none of the above solutions helped. I was in the middle of upgrading react native in a create-react-native-app project until I found out that not all versions of Expo support the latest React Native.
Found this page linked in the documentation that shows which version combinations of React Native, React, and Expo are officially supported:
Source: https://github.com/react-community/create-react-native-app/blob/master/VERSIONS.md
Editing the app.json and package.json files to match the corresponding versions and running npm install got everything working again.
I am using a physical device, in my case this solved the problem:
Uninstall the app
lsof -i :8081
kill -9 PID
Rebuild the app (react-native run-android or react-native run-ios)
In your build.gradle file add the following
implementation ("com.facebook.react:react-native:0.51.0") {
force = true;
}
replace 0.51.0 with the version in your package.json
Try installing the dependencies again. That worked for me-
1.) yarn/npm install
2.) yarn/npm start --reset-cache
For me it was due to react-native version in dependency section of package.json file. It was:
"dependencies": {
"expo": "^27.0.1",
"react": "16.3.1",
"react-native": "~0.55.0"
}
I chaged it to:
"dependencies": {
"expo": "^27.0.1",
"react": "16.3.1",
"react-native": "0.52.0"
}
Now it works fine.
In my case installing a new virtual device helped. Now I am using 1 device per app.
It happens sometimes when you try to run without closing the node server, in which the previous app was running, so try restarting React.To do so, just run the following commands:
1. To kill current processes
killall node -9
2. To Start React Native
react-native start
3. Then Run android
react-native run-android
For my case I'm facing it on iOS, and I've tried to reset and clear all cache using below command but failed too, despite many comments saying that the root cause is there is react packager running somewhere accidentally, I've restarted my mac and the problem still remained.
watchman watch-del-all && rm -rf node_modules/ && yarn cache clean && yarn install && yarn start --reset-cache
The solution is, to delete the build folder # /ios/build, then execute react-native run-ios solved it
I have tried the solutions above but adding this to AndroidManifest.xml seems to fix it.
android:usesCleartextTraffic="true"
For others with the same problem on iOS with CocoaPods:
I tried all of the solutions above, without luck. I have some packages with native dependencies in my project, and some of those needed pod modules being installed. The problem was that React was specified in my Podfile, but the React pod didn't automatically get upgraded by using react-native-git-upgrade.
The fix is to upgrade all installed pods, by running cd ios && pod install.
Expo users - make sure your app.json sdk version and package.json expo version are (may be equal) compatible to each other.
The fix we did was to make sure the ANDROID_HOME and PATH variables were set up prior to the build.
First, run the below two commands then the build the app for the device.
export ANDROID_HOME=/Users/username/MyFiles/applications/androidsdk
export PATH=$PATH:$ANDROID_HOME/tools:$ANDROID_HOME/platform-tools
This is working for me :
react-native start --reset-cache
I also had this issue using Expo and iOS Simulator. What worked for me was erasing the Simulator in Hardware > Erase All Content and Settings...
I have got the same issue while building my react native app for android and I did the following which worked for me.
The "JavaScript version 0.50.1" in the error console is the react-native version in your package.json file. Make sure it is the same version as "Native version 0.50.0" in the error console.
I have Updated the react-native version to the "Native Version 0.50.0" as prompted in the error console.
Rebuild the app react-native run-android.
Possible Fix:
Delete the package-lock.json
Run: watchman watch-del-all && rm -rf $TMPDIR/react-* && rm -rf $TMPDIR/haste-map-react-native-packager-* && rm -rf node_modules/&& npm install
If the problem persists, try to execute the project directly from the Xcode
This worked for me.
In my case (NOT using expo & Android build)
package.json
"dependencies": {
"react": "16.3.1",
"react-native": "0.55.2"
}
And app.json
{
"sdkVersion": "27"
}
resolved the issue
I was trying to build and run a React Native app from WebStorm and ran into this problem. The simple solution for me was:
watchman watch-del-all
On macOS, if watchman is not already installed, install it using Homebrew:
brew install watchman
In my case, I changed the expo version manually. I got the same issue because I forgot to update sdkVersion in app.json and babel-preset-expo in package.json
After that run: expo r -c to clear cache and start the app.
This Answer is Published in 2020,
Fix this Error in 3 steps:
First step: I changed the value of expo in package.json file to the latest supported version, according to expo documents(visit here).
Second step: I changed the value of sdkVersion in app.json file to the same value of expo in package.json.( equal number to last step).
Third step : I changed the value of react-native in package.json file to the same value of React Native Version , according to expo documents(visit here).
now your ready to go.
use npm install to install specified version of dependencies and then npm start to run the project
I got this classing when TypeScript type definitions mismatched.
E.G react-native at 0.61.5 in dependencies and #types/react-native at 0.60.0 in devDependencies.
As soon as I updated devDependencies it worked. Didn't have to restart anything.
edit your package.json for your javascript version
"react-native": "^0.50.1",
after run
npm install
For me, who is running with a monorepo, there was a hidden react-native version inside yarn.lock. It was not present in any package.json, but was never deleted.
I removed that particular react-native version from yarn.lock, and did a
yarn install
This cleaned out alot of old stuff and made sure that things was working fine.