react-native deploy to android device error 3 activity class does not exist

Question

My app works fine on my simulator so now I am trying to put it on my phone. When I try install I get the following message

...
BUILD SUCCESSFUL
Total time: 15.578 secs

This build could be faster, please consider using the Gradle Daemon: http://gradle.org/docs/2.4/userguide/gradle_daemon.html
Starting the app (/usr/local/opt/android-sdk/platform-tools/adb shell am start -n com.ethicalfishing/.MainActivity)...
Starting: Intent { cmp=com.ethicalfishing/.MainActivity }
Error type 3
Error: Activity class {com.ethicalfishing/com.ethicalfishing.MainActivity} does not exist.

I understand this error has been spoken about relating to non-react-native apps, however the solutions given were either not relevant or not helpful (or I didn't understand them)

Answer 1

I had the same problem. I found that build.gradle's applicationId and AndroidManifest.xml package were different.

build.gradle:

defaultConfig {
    applicationId "com.example.yourapp"
    minSdkVersion 16
    targetSdkVersion 22
    versionCode 1
    versionName "1.0"
    ndk {
        abiFilters "armeabi-v7a", "x86"
    }

That was the problem in my case.