[Flutter 3.22 & 3.24] ARFoundation crashes on Android < 13 - NoClassDefFoundError: Landroid/window/OnBackInvokedCallback #21
Comments
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Narrowed it down to this commit on Flutter master. |
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With some custom plugin modifications I managed to try this on Unity 2023.2.20 and 6000.0.7. I'm still getting the same error, so I will probably have to open an issue in the Flutter repo. 2023.2.20 6000 |
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After a report in the Flutter repo this can be labeled as a Unity issue. The causeOnce AR boots up, Unity uses the The What nowFlutter won't stop using this class for a few people using the niche use-case of embedding Unity with AR. With some luck a try-catch around However this means either:
I've tried to decompile unity-classes.jar, but none of the decompilers that I could find returned valid code that could compile again without errors. Unity reproductionTo replicate this issue witthout Flutter:
TLDR (too long didn't read)AR is broken with Flutter 3.22+. Don't expect this to be fixed for months, if at all. |
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Thanks again for your tireless and meticulous work tracking all of this @timbotimbo it's very much appreciated. I've added a note to the README for this issue. |
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This is now in the Unity issue tracker. They seem to have omitted most details from my bug report, but I guess it is a first step. Anyone affect by this should probably upvote this in the issuetracker. |
timbotimbo
changed the title
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Unity got back to me on the bug report, calling it "By Design". Given that Flutter devs point me at Unity, and Unity considers it by design, AR is likely a lost cause on Android < 13. |
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I took a final look at this and actually found a simple workaround. This because the FlutterFragmentActivity did not (yet?) get updated with the WorkaroundUpdate MainActivity.kt to use this: import io.flutter.embedding.android.FlutterFragmentActivity;
class MainActivity: FlutterFragmentActivity() {
}I tested ARFoundation on a Galaxy S8 with Android 9 on these Flutter versions:
This workaround should allow AR apps stuck on Flutter 3.1x to upgrade to 3.22+. Drawbacks and side effectsI'm still playing around with this so this list might not be complete yet.
<!-- Androidmanifest -->
<application
...
android:enableOnBackInvokedCallback="false">So if you want to test this workaround, pay extra attention to the 'back' behavior in your app. |
… app facing package to 1.2.4 to publish update to README to pub.dev
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Thanks for the detailed update @timbotimbo this is really appreciated. I have updated the README to note that there is a workaround documented in this issue, but that it may break in future versions of Flutter. |
Description
Since Flutter 3.22, Unity will crash on certain Android versions when ARFoundation is activated.
This only happens on Android <13.
This might also affect other unity plugins using native code, I just noticed it using ARFoundation.
In my own project Unity works fine for 3D scenes but crashes when I switch to a scene that includes ARFoundation.
In the example project here, Unity shows up with the Flutter logo but crashes once the AR support check runs.
Error in the console:
Looking up OnBackInvokedCallback, it is added in API 33 (android 13) and is related to the predictive back gesture in Android 14.
I'm not sure if this is a flutter bug where it sends some kind of message which it shouldn't on API <33, or if it is caused by Unity missing an implementation.
Error log
Full console log up to the crash
Flutter version
Crashed on:
Did not crash on:
Unity version
Only tested with:
2022.3.21f1, 2022.3.33f1
ArFoundation 5.1.2 and 5.1.4
Minimum reproducible example
flutter_embed_unityfolder from this repoexample_unity_2022_3_projectfolder from this repo.The only change applied to build the example was to change the android sdk to 34 in the gradle files.
Any project using AR with android <13 will likely work to trigger this.
Android devices
Devices without crash:
Devices with crash:
Some things I've tried
-keep class android.window.** { *; }-keep class android.window.OnBackInvokedCallback { *; }.android:enableOnBackInvokedCallback="false"to all androidmanifest activities and applications.implementation "androidx.activity:activity:1.6.0in gradle(OnbackInvokedCallback is mentioned in the changes.)
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