[Android] Detox cannot connect to app

[aaronpliu]

Did you test using the latest Detox?

• I have tested this issue on the latest Detox release and it still reproduces.

Did your test fail and you're not sure why?

• I have read the troubleshooting guide and it didn't help me.

What happened?

When minify enabled, it's not working for Detox androidTest/ apk even if reference detox app rules.
When minify disabled, it's ok to work.

What was the expected behaviour?

1. No need to build androidTest every time (unless required change)
2. Detox apk is working for Android release build

Help us reproduce this issue!

minify enabled, build release(./gradlew app:assembleRelease) and androidTest (./gradlew assembleAndroidTest -DtestBuildType=release) separately

In what environment did this happen?

Detox version: 20.41.3
React Native version: 0.79.4
Has Fabric (React Native's new rendering system) enabled: (yes/no)
Node version: 18.20.4
Device model: Android emulator
Android version: 15
Test-runner (select one): jest / other

Detox logs

Detox logs

2025-09-22T09:44:18.442Z detox WARN:  i device An error occurred while waiting for the app to become ready. Waiting for disconnection...
  error: Failed to run application on the device
  
  HINT: Most likely, your main activity has crashed prematurely.
  
  Native stacktrace dump:
  java.lang.NoClassDefFoundError: Failed resolution of: Lkotlin/jvm/internal/Intrinsics;
        at androidx.test.platform.app.AppComponentFactoryRegistry.instantiateApplication(Unknown Source:2)
        at androidx.test.runner.MonitoringInstrumentation.newApplication(MonitoringInstrumentation.java:151)
        at androidx.test.runner.AndroidJUnitRunner.newApplication(AndroidJUnitRunner.java:300)
        at android.app.LoadedApk.makeApplicationInner(LoadedApk.java:1479)
        at android.app.LoadedApk.makeApplicationInner(LoadedApk.java:1411)
        at android.app.ActivityThread.handleBindApplication(ActivityThread.java:7790)
        at android.app.ActivityThread.-$$Nest$mhandleBindApplication(Unknown Source:0)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2546)
        at android.os.Handler.dispatchMessage(Handler.java:110)
        at android.os.Looper.loopOnce(Looper.java:248)
        at android.os.Looper.loop(Looper.java:338)
        at android.app.ActivityThread.main(ActivityThread.java:9067)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:593)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:932)
  Caused by: java.lang.ClassNotFoundException: kotlin.jvm.internal.Intrinsics
        ... 15 more
  
2025-09-22T09:44:18.442Z detox WARN:  i device The app disconnected.

Device logs

Device logs

paste your device.log here!

More data, please!

No response

[aaronpliu]

I found #4753, seems no solution yet. @gosha212 @noomorph

[gosha212]

Hi @aaronpliu . Thanks for the report. It should be easy to be fixed on your side unless we fix it on ours. Just add
-keep class kotlin.jvm.internal.Intrinsics { *; }
to your proguard rules

[aaronpliu]

Hi @aaronpliu . Thanks for the report. It should be easy to be fixed on your side unless we fix it on ours. Just add -keep class kotlin.jvm.internal.Intrinsics { *; } to your proguard rules

Thanks for your checking. I added it in proguard rules, the app shows a black screen after launching (it would launch app compared to previous error). Anything else to handle?

[gosha212]

@aaronpliu We need some logs from device. Do you see any errors?

[aaronpliu]

No. it's stuck and fail test case after a period of time.

I have another question. Can I have app release build and androidTest/ build separately? then don't need to build androidTest/ every time. It's ok if minify is disabled. Now it said detox server disconnected after app launched.

[gosha212]

can you share an example app? Why do you need to build the app? If you change only the JS you don't need to build. just run detox test

[gosha212]

@aaronpliu how is going? did it work for you? can we get more logs?
Can you run detox test -l trace?

[aaronpliu]

can you share an example app? Why do you need to build the app? If you change only the JS you don't need to build. just run detox test

configured detox androidTest and build with release app. got adnroidTest.apk and release-app.apk. since no change in native code and update the JS only, no need to build androidTest.apk every time. then take new version of release-app.apk to test. It was working good all the time (unless RN upgrade or some of change in android native code, then no need to build androidTest apk).

For now, after minifyEnabled=true in android, I've added proguard rules and re-build release-app.apk and androidTest.apk together. it would be run. However, I don't want to build androidTest.apk every time since there are many environment to build for each release. Now the androidTest.apk cannot work with new release of release-app.apk. thus it force me to build androidTest apk and release app apk together every time, it will need more time to build all of environments. Not sure if there is any relationship after minifyEnabled=true, if disabled, then it's ok to run with any release-app.apk.

the project has added
-keep class kotlin.jvm.** { *; } in proguards

error log:

2025-10-11T14:32:58.441Z detox DEBUG: �[90mi�[39m �[33mchild-process�[39m�[90m:SPAWN_CMD�[39m /Users/macmm/Library/Android/sdk/platform-tools/adb -s emulator-17518 shell am instrument -w -r -e detoxServer ws://localhost:49839 -e detoxSessionId 9fb9a063-adf3-3f6f-c5da-fb7bba0a3307 -e detoxURLBlacklistRegex ("https://clients3.google.com*") -e detoxEnableSynchronization 0 -e debug false com.inka.sp.test/androidx.test.runner.AndroidJUnitRunner
2025-10-11T14:32:58.945Z detox DEBUG: �[90mi�[39m �[33mchild-process�[39m�[90m:EXEC_CMD�[39m "/Users/aaronpliu/Library/Android/sdk/platform-tools/adb" -s emulator-17518 shell "ps | grep "com.inka.sp$""
2025-10-11T14:32:59.144Z detox TRACE: �[90mi�[39m �[33mchild-process�[39m�[90m:SPAWN_STDOUT�[39m INSTRUMENTATION_STATUS: stack=java.lang.NoClassDefFoundError: Failed resolution of: Lkotlin/jvm/internal/Intrinsics;
at androidx.test.platform.app.AppComponentFactoryRegistry.instantiateApplication(Unknown Source:2)
at androidx.test.runner.MonitoringInstrumentation.newApplication(MonitoringInstrumentation.java:151)
at androidx.test.runner.AndroidJUnitRunner.newApplication(AndroidJUnitRunner.java:300)
at android.app.LoadedApk.makeApplicationInner(LoadedApk.java:1479)
at android.app.LoadedApk.makeApplicationInner(LoadedApk.java:1411)
at android.app.ActivityThread.handleBindApplication(ActivityThread.java:7790)
at android.app.ActivityThread.-$$Nest$mhandleBindApplication(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2546)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.loopOnce(Looper.java:248)
at android.os.Looper.loop(Looper.java:338)
at android.app.ActivityThread.main(ActivityThread.java:9067)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:593)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:932)
Caused by: java.lang.ClassNotFoundException: kotlin.jvm.internal.Intrinsics
... 15 more

INSTRUMENTATION_STATUS: stream=
Process crashed before executing the test(s):
java.lang.NoClassDefFoundError: Failed resolution of: Lkotlin/jvm/internal/Intrinsics;
at androidx.test.platform.app.AppComponentFactoryRegistry.instantiateApplication(Unknown Source:2)
at androidx.test.runner.MonitoringInstrumentation.newApplication(MonitoringInstrumentation.java:151)
at androidx.test.runner.AndroidJUnitRunner.newApplication(AndroidJUnitRunner.java:300)
at android.app.LoadedApk.makeApplicationInner(LoadedApk.java:1479)
at android.app.LoadedApk.makeApplicationInner(LoadedApk.java:1411)
at android.app.ActivityThread.handleBindApplication(ActivityThread.java:7790)
at android.app.ActivityThread.-$$Nest$mhandleBindApplication(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2546)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.loopOnce(Looper.java:248)
at android.os.Looper.loop(Looper.java:338)
at android.app.ActivityThread.main(ActivityThread.java:9067)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:593)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:932)
Caused by: java.lang.ClassNotFoundException: kotlin.jvm.internal.Intrinsics
... 15 more

INSTRUMENTATION_STATUS_CODE: -2

2025-10-11T14:32:59.167Z detox TRACE: �[90mi�[39m �[33mchild-process�[39m�[90m:SPAWN_STDOUT�[39m INSTRUMENTATION_RESULT: shortMsg=Process crashed.

2025-10-11T14:32:59.168Z detox TRACE: �[90mi�[39m �[33mchild-process�[39m�[90m:SPAWN_STDOUT�[39m INSTRUMENTATION_CODE: 0

[gosha212]

@aaronpliu did you try to rebuild? clean every thing a build again