Symbolication

Symbolication Pipelines

Instructions

A crash without symbols is noise. Treat symbol upload as a release-blocker, automate it in CI, and verify symbols are resolvable before each release is promoted.

1. Why Symbols Matter

• iOS ships stripped binaries; stack traces contain addresses that must be resolved via dSYMs.
• Android release builds run R8 which renames classes and methods; mapping files reverse the renaming. NDK libraries ship stripped; .so.sym files provide native frames.
• Flutter release builds are AOT-compiled Dart; with --split-debug-info the debug symbols are emitted as a separate directory.
• React Native minifies JS and (with Hermes) compiles to bytecode; source maps are needed to recover JS frames.

2. iOS -- dSYMs

Xcode build settings:

• DEBUG_INFORMATION_FORMAT = dwarf-with-dsym for Release.
• STRIP_INSTALLED_PRODUCT = YES, COPY_PHASE_STRIP = NO.
• ENABLE_BITCODE = NO (bitcode is deprecated since Xcode 14).

Automated upload via Fastlane:

lane :upload_symbols do
  dsym_zip = "build/MyApp.xcarchive/dSYMs"
  upload_symbols_to_crashlytics(
    dsym_path: dsym_zip,
    gsp_path: "ios/MyApp/GoogleService-Info.plist"
  )
  sentry_upload_dif(
    auth_token: ENV["SENTRY_AUTH_TOKEN"],
    org_slug: "my-org",
    project_slug: "my-app-ios",
    path: dsym_zip,
    include_sources: true
  )
end

If you enable App Store phased release, download dSYMs from App Store Connect within 24 hours (fastlane download_dsyms) because bitcode-recompiled binaries have different UUIDs.

3. Android -- Mapping Files

// app/build.gradle.kts
android {
    buildTypes {
        release {
            isMinifyEnabled = true
            isShrinkResources = true
            proguardFiles(
                getDefaultProguardFile("proguard-android-optimize.txt"),
                "proguard-rules.pro"
            )
        }
    }
}

Crashlytics Gradle plugin (com.google.firebase.crashlytics) uploads mapping.txt automatically when mappingFileUploadEnabled = true.

For Sentry:

sentry {
    autoUploadProguardMapping.set(true)
    includeProguardMapping.set(true)
}

For Datadog:

datadog {
    checkProjectDependencies = "warn"
}

and run ./gradlew app:uploadMappingRelease in CI.

Always keep the mapping file as a build artifact for 6+ months. The mapping is the only key to reading back obfuscated stack traces.

4. Android -- Native Symbols (NDK)

• Configure android.buildTypes.release.ndk { debugSymbolLevel = "FULL" }.
• Crashlytics Gradle plugin uploads via nativeSymbolUploadEnabled = true.
• Sentry: sentry { uploadNativeSymbols.set(true) }.
• For manual vendors, upload the build/intermediates/merged_native_libs/release/out/lib/<abi>/*.so unstripped copies.

5. Flutter -- Dart Symbols

Build release with split debug info:

flutter build apk --release --obfuscate --split-debug-info=build/symbols
flutter build ios --release --obfuscate --split-debug-info=build/symbols

Upload:

sentry-cli debug-files upload --org my-org --project my-app-flutter build/symbols
firebase crashlytics:symbols:upload --app <app-id> build/symbols  # via the Flutter Firebase CLI

Without --split-debug-info Dart frames in release will be addresses, not function names.

6. React Native -- Source Maps and Hermes

For Hermes (default since RN 0.70):

# iOS
react-native bundle --platform ios --dev false --entry-file index.js \
  --bundle-output ios-release.bundle \
  --sourcemap-output ios-release.bundle.map
node_modules/react-native/sdks/hermesc/osx-bin/hermesc \
  -emit-binary -output-source-map ios-release.bundle \
  -out ios-release.hbc

# Upload to Sentry
sentry-cli sourcemaps upload --release "my-app@${VERSION}+${BUILD}" \
  --dist ios ios-release.bundle ios-release.bundle.map

Repeat for Android with android-release.bundle + .map. Use @sentry/react-native CLI helpers (sentry-expo upload-sourcemaps) where applicable.

7. CI Integration

A sample GitHub Actions step that fails the release build if symbols cannot be uploaded:

- name: Upload symbols
  if: github.ref_type == 'tag'
  env:
    SENTRY_AUTH_TOKEN: ${{ secrets.SENTRY_AUTH_TOKEN }}
  run: |
    set -euo pipefail
    sentry-cli debug-files upload --org my-org --project my-app-android \
      app/build/outputs/mapping/release/mapping.txt \
      app/build/intermediates/merged_native_libs/release/out/lib
    sentry-cli sourcemaps upload \
      --release "my-app@${VERSION}+${BUILD}" --dist android \
      android-release.bundle android-release.bundle.map

Store a checksum of each uploaded symbol in a release manifest so you can later prove which symbols exist for which build id.

8. Verification

Before promoting a release:

1. Trigger a forced crash in a release build on a staging device.
2. Confirm the resulting issue shows function names and line numbers in Crashlytics/Sentry/Datadog.
3. Confirm native frames (if any) are resolved, not ??? or raw hex addresses.
4. Confirm the issue is associated with the correct release identifier.

If any step fails, block the release until symbols are fixed.

Checklist

• iOS: dwarf-with-dsym enabled, dSYMs uploaded by CI to every vendor.
• Android: R8 mapping and NDK native symbols uploaded automatically.
• Flutter: --obfuscate --split-debug-info used; symbols uploaded.
• React Native: bundle + source map (Hermes) uploaded with matching release/dist.
• Mapping files are archived as build artifacts for 6+ months.
• CI release step fails if symbol upload fails.
• A forced-crash verification is run per release before rollout.