How to set canOverrideExistingModule=true in React Native for Android Apps?

Question

I built an android app using React Native, it got built successfully but when I run the app in my Android Virtual Device it shows up a full red screen with the following error:

I have not done native app development ever before neither do I have any knowledge of Java so I have no idea what this error means and how to fix this.

Answer 1

The name of the package associated to this error is not AirMapModule but MapsPackage from com.airbnb.android.react.maps.

In your MainApplication.java in directory : android/app/src/main/java/../../ remove any duplicate entry of :

• the import package : import com.airbnb.android.react.maps.MapsPackage
• the call to the constructor of the module : new MapsPackage() in function getPackages

Answer 2

Go to file "MainApplication.java" (under .\android\app\src\main\java\com\projectName\)

Make sure that under getPackages() function you don't have duplicate lines (in my case I had "new MapsPackage()" twice).

Fix duplicate imports as well.

Answer 3

Open the MainApplication.java file by this address: android/app/src/main/java/com/projectName/MainApplication.java and add the following code to MainApplication.java file:

@Override    
public boolean canOverrideExistingModule() {        
  return true;    
}   

And everything became correct.

Answer 4

Go to the MainAplication file.

Remove duplicate package and remove duplicate package in getPackages() method

  @Override
    protected List<ReactPackage> getPackages() {
      return Arrays.<ReactPackage>asList(
          new MainReactPackage(),
            new VectorIconsPackage()
      );
    }

Then after try this command in your terminal :

• cd android
• ./gradlew clean

Answer 5

The above solutions are all correct, but let me explain a little bit,some of above solutions suggest to override the following method.

@Override    
public boolean canOverrideExistingModule() {        
  return true;    
} 

But question is where to override? first of all, you can't override inside MainActivity.java or MainApplication.java file.

You should override it in the class inside some node_modules project folder and that class will be extending from ReactContextBaseJavaModule class.

In my case, it was not getting repeated in imports/adding duplicate packages but it was mainly because of auto linking at the and that was making it to repeat.

I am using react-native-contacts npm package to interact so what I did is that went inside

node_modules\react-native-contacts\android\src\main\java\comrt2zz\reactnativecontacts\ 
ContactsManager.java 

and this ContactsManager was extending from the ReactContextBaseJavaModule and I override there and got the problem resolved.

So as general there could be a lot of classes that will be extending from ReactContextBaseJavaModule under different projects inside node_modules, but you need to go for specific a project that will be creating duplication problem and there you should override it.

Answer 6

If the version of RN you're using is >= 0.60 then there is the possibility that auto-linking and your manual linking are doing the same thing twice. You have two options:

1- You can revert code changes in getPackages method
2- You can disable auto linking in react-native-config.js file.

Answer 7

You can remove your package from MainApplication.java

Answer 8

Go to your module (coz of which you are getting this error message) Open the module.. add this code to it...

@Override    
public boolean canOverrideExistingModule() {        
  return true;    
}   

Answer 9

You can try check in file MainApplication.java in directory : android\app\src\main\java is have any duplicate package AirMapModule exist or not, and delete 1 if have.

Answer 10

Solution

Goto android/app/src/main/java/YOURPACKAGE/MainApplication.java

Find method getPackages();

Remove this packages.add(new MapsPackage());

Chill Pill! :)

Answer 11

Add only the modules which are not autolinked at here,

        @Override
        protected List<ReactPackage> getPackages() {
          @SuppressWarnings("UnnecessaryLocalVariable")
          List<ReactPackage> packages = new PackageList(this).getPackages();
          // Packages that cannot be autolinked yet can be added manually here, for 
          // example: packages.add(new MyReactNativePackage());         
          return packages;
        }

If the module is autolinked and added the module here, you will get this error.

Answer 12

check your MainApplication.java, in particular protected List<ReactPackage> getPackages(); the AirMapModule is probably twice in the list

Answer 13

just remove packages.add(new MapsPackage()); this line MainApplication.java

Answer 14

if installed library react-navigation you can run via android studio. else remove library react-navigation and just yarn it's will work.