Crashlytics: debugging why crashes don't appear from an iXGuard protected app

[darrentaft]

We've been working with GuardSquare for the past 2 months trying to find why our react native app is no longer submitted crash reports from our iOS build, but we've reached a dead end. I tried raising a support request with the Firebase support team for iOS, however they said they don't support iXGuard, and to raise it here instead.

Our Android app works fine, and our iOS app was working OK for months - crash reports were being submitted and appearing on the dashboard. This stopped earlier this year, but we're unable to identify specifically when - we can't find any correlation between our builds, and when it stopped working. It's also not 100% failure - sometimes a build will successfully send a single crash report, but then never send any again after that from that device.

We've identified that everything works correctly when the app isn't processed with iXGuard, and we've also confirmed that using xcrun strip with the -sX flag also works, however when full protection is enabled, the crash reports stop working.

This is the message from GuardSquare:

We have also thoroughly analyzed the Firebase Crashlytics iOS source code, and debugged your application with LLDB. Comparing a broken and a functioning version of your app has shown that in both cases the application is successfully connecting with the Crashlytics server and sending out crash information (https://github.com/firebase/firebase-ios-sdk/blob/main/Crashlytics/Crashlytics/Controllers/FIRCLSReportUploader.m#L216).

As we have no visibility or control over what happens on the Crashlytics server side, there is little more we can do at this point. We suggest you take steps to involve the Firebase Crashlytics support to resolve this issue. Naturally, we are available to provide technical details to support you in the conversation with Crashlytics if needed.

We're using @react-native-firebase/crashlytics@25.1.0 but have tried many different versions.