feat: v8: Capture app start errors before JS #5582

antonis · 2026-01-26T16:42:07Z

📢 Type of change

Bugfix
New feature
Enhancement
Refactoring

📜 Description

Follow up to #4472 (v6) > #5470 (v7) targeting v8 #5501

Capture App Start errors and crashes by initializing Sentry from sentry.options.json (#4472)

Create sentry.options.json in the React Native project root and set options the same as you currently have in Sentry.init in JS.

{
    "dsn": "https://key@example.io/value",
}

Initialize Sentry on the native layers by newly provided native methods.

import io.sentry.react.RNSentrySDK

class MainApplication : Application(), ReactApplication {
    override fun onCreate() {
        super.onCreate()
        RNSentrySDK.init(this)
    }
}

#import <RNSentry/RNSentry.h>

@implementation AppDelegate
- (BOOL)application:(UIApplication *)application
    didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    [RNSentrySDK start];
    return [super application:application didFinishLaunchingWithOptions:launchOptions];
}
@end

Add RNSentrySDK APIs support to @sentry/react-native/expo plugin (#4633)
- Adds useNativeInit option to automatically initialize Sentry natively before JavaScript loads, enabling capture of app start errors
```
{
  "expo": {
    "plugins": [
      [
        "@sentry/react-native/expo",
        {
          "useNativeInit": true
        }
      ]
    ]
  }
}
```

Changes

Load optionsFile into the JS bundle during Metro bundle process (#4476)
Add experimental version of startWithConfigureOptions for Apple platforms (#4444)
Add experimental version of init with optional OptionsConfiguration<SentryAndroidOptions> for Android (#4451)
Add initialization using sentry.options.json for Apple platforms (#4447)
Add initialization using sentry.options.json for Android (#4451)
Merge options from file with Sentry.init options in JS (#4510)

Internal

Extract iOS native initialization to standalone structures (#4442)
Extract Android native initialization to standalone structures (#4445)

Note

The feature the feature should be 100% backwards compatible and opt-in. Users who don't create sentry.options.json or call RNSentrySDK.start()/init() will experience zero changes to their existing Sentry implementation. The traditional JS-only initialization path remains fully functional and is the default behavior.

📝 Documentation PR: getsentry/sentry-docs#16170

💡 Motivation and Context

Fixes #3608

Previously, React Native apps couldn't capture errors that occurred during app startup before JavaScript initialized, because Sentry was only initialized from JavaScript code (Sentry.init()). This meant crashes during:

Native module initialization
JavaScript bundle loading
Early React Native bridge setup

were never captured.

💚 How did you test it?

CI, Manually

📝 Checklist

I added tests to verify changes
No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled
I updated the docs if needed.
I updated the wizard if needed.
All tests passing
No breaking changes

🔮 Next steps

#skip-changelog

…ructures (#4445) * Extract Android SDK Init * Update tests * Adds changelog * Fix lint issues * Rename RNSentryStart instance for clarity * Converts RNSentryStart to utility class * Update CHANGELOG.md --------- Co-authored-by: Krystof Woldrich <31292499+krystofwoldrich@users.noreply.github.com>

…platforms (#4444)

* Convert json object to writable map * Make class/methods package-private(default)

…4451)

)

…4533)

…mple (#4535)

)

#4561)

…4595)

- Resolved merge conflicts across iOS, Android, and JavaScript/TypeScript code - Updated iOS implementation to use RNSentryStart API - Fixed Android compilation errors for Sentry Android SDK v7 compatibility - Removed deprecated API calls (setEnableTracing, getPackages, getIntegrations) - Updated Gradle build scripts and resolved conflict markers - All builds verified: iOS, Android, and Expo sample apps compile successfully

github-actions · 2026-01-26T17:06:10Z

iOS (new) Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1209.73 ms	1209.33 ms	-0.40 ms
Size	3.38 MiB	4.68 MiB	1.30 MiB

Baseline results on branch: v8

Startup times

Revision	Plain	With Sentry	Diff
`206e87e`+dirty	1197.12 ms	1204.25 ms	7.13 ms
`b4fa5b4`+dirty	1213.59 ms	1211.26 ms	-2.33 ms
`d6aa223`+dirty	1216.76 ms	1213.40 ms	-3.37 ms
`12fba4a`+dirty	1209.43 ms	1217.08 ms	7.65 ms
`bc8a1ed`+dirty	1198.66 ms	1200.60 ms	1.94 ms
`fa0d109`+dirty	1206.81 ms	1205.38 ms	-1.43 ms

App size

Revision	Plain	With Sentry	Diff
`206e87e`+dirty	3.38 MiB	4.67 MiB	1.29 MiB
`b4fa5b4`+dirty	3.44 MiB	4.66 MiB	1.22 MiB
`d6aa223`+dirty	3.38 MiB	4.67 MiB	1.29 MiB
`12fba4a`+dirty	3.38 MiB	4.67 MiB	1.29 MiB
`bc8a1ed`+dirty	3.44 MiB	4.66 MiB	1.22 MiB
`fa0d109`+dirty	3.38 MiB	4.67 MiB	1.29 MiB

Previous results on branch: antonis/capture-app-start-errors-v8

Startup times

Revision	Plain	With Sentry	Diff
`88812b1`+dirty	1210.98 ms	1215.22 ms	4.24 ms
`82de722`+dirty	1210.87 ms	1217.00 ms	6.13 ms
`b4df5a0`+dirty	1217.06 ms	1221.61 ms	4.55 ms

App size

Revision	Plain	With Sentry	Diff
`88812b1`+dirty	3.38 MiB	4.67 MiB	1.29 MiB
`82de722`+dirty	3.38 MiB	4.67 MiB	1.29 MiB
`b4df5a0`+dirty	3.38 MiB	4.67 MiB	1.29 MiB

github-actions · 2026-01-26T17:13:33Z

iOS (legacy) Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1196.92 ms	1203.92 ms	7.00 ms
Size	3.38 MiB	4.68 MiB	1.30 MiB

Baseline results on branch: v8

Startup times

Revision	Plain	With Sentry	Diff
`206e87e`+dirty	1184.11 ms	1183.19 ms	-0.92 ms
`b4fa5b4`+dirty	1203.83 ms	1207.13 ms	3.30 ms
`d6aa223`+dirty	1192.33 ms	1208.17 ms	15.84 ms
`12fba4a`+dirty	1214.20 ms	1223.30 ms	9.09 ms
`bc8a1ed`+dirty	1194.70 ms	1201.18 ms	6.48 ms
`fa0d109`+dirty	1216.02 ms	1220.67 ms	4.65 ms

App size

Revision	Plain	With Sentry	Diff
`206e87e`+dirty	3.38 MiB	4.67 MiB	1.29 MiB
`b4fa5b4`+dirty	3.44 MiB	4.66 MiB	1.22 MiB
`d6aa223`+dirty	3.38 MiB	4.67 MiB	1.29 MiB
`12fba4a`+dirty	3.38 MiB	4.67 MiB	1.29 MiB
`bc8a1ed`+dirty	3.44 MiB	4.66 MiB	1.22 MiB
`fa0d109`+dirty	3.38 MiB	4.67 MiB	1.29 MiB

Previous results on branch: antonis/capture-app-start-errors-v8

Startup times

Revision	Plain	With Sentry	Diff
`88812b1`+dirty	1216.63 ms	1215.55 ms	-1.08 ms
`82de722`+dirty	1213.09 ms	1208.90 ms	-4.19 ms
`b4df5a0`+dirty	1213.04 ms	1218.59 ms	5.55 ms

App size

Revision	Plain	With Sentry	Diff
`88812b1`+dirty	3.38 MiB	4.67 MiB	1.29 MiB
`82de722`+dirty	3.38 MiB	4.67 MiB	1.29 MiB
`b4df5a0`+dirty	3.38 MiB	4.67 MiB	1.29 MiB

antonis · 2026-01-27T09:37:47Z

@sentry review

lucas-zimerman · 2026-01-27T11:22:17Z

No noticeable impact on iOS, the app size increase by adding sentry on java is interesting though, but no extra impact from this PR.

antonis · 2026-01-27T11:25:14Z

No noticeable impact on iOS, the app size increase by adding sentry on java is interesting though, but no extra impact from this PR.

That's a good catch @lucas-zimerman 🤔

I wonder if this has to do with the Gradle Plugin bump #5578 on the v8 base branch #5501

lucas-zimerman · 2026-01-27T11:28:42Z

CHANGELOG.md

+        [
+          "@sentry/react-native/expo",
+          {
+            "useNativeInit": true


Q: Do all sentry options work here? we should document this feature.

This is the only added option in the plugin. I've started a documentation PR in getsentry/sentry-docs#16170

antonis · 2026-01-27T12:04:27Z

No noticeable impact on iOS, the app size increase by adding sentry on java is interesting though, but no extra impact from this PR.

That's a good catch @lucas-zimerman 🤔

I wonder if this has to do with the Gradle Plugin bump #5578 on the v8 base branch #5501

Looking at it again I think the With Sentry sizes are the same with the base branch 48.40 MiB (legacy), 49.22 MiB (new)

lucas-zimerman

After a complete PR review and also loads of tokens, I can really say, LGTM!

packages/core/scripts/sentry-xcode.sh

packages/core/ios/RNSentry.mm

Co-authored-by: LucasZF <lucas-zimerman1@hotmail.com>

# Conflicts: # CHANGELOG.md

antonis · 2026-01-27T15:28:09Z

@sentry review

packages/core/android/src/main/java/io/sentry/react/RNSentryStart.java

* fix(android): Fix ConcurrentModificationException when disabling native crash handling When enableNativeCrashHandling is set to false, the code was iterating over the integrations list with a for-each loop while calling remove() directly, which causes a ConcurrentModificationException at runtime. Fixed by using Java 8's removeIf() method which safely handles iteration and removal in a single operation. This is more concise and follows modern Java best practices. Added unit tests to verify the fix and ensure integrations are properly removed without throwing exceptions. Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com> * Lint fix --------- Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

packages/core/android/src/main/java/io/sentry/react/RNSentryStart.java

…carUrl The code attempted to read defaultSidecarUrl without checking if the key exists in the options map. This caused a NoSuchKeyException crash during startup when spotlight was set to true in sentry.options.json without providing defaultSidecarUrl. Added key existence check to match iOS implementation behavior and prevent the crash while maintaining backward compatibility. Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

* test(e2e): Add auto init from JS tests for Android Implements Android E2E testing infrastructure to verify both manual native initialization and auto initialization from JavaScript, matching the iOS implementation and resolving issue #4912. Key additions: - Jest configs for android.auto and android.manual test modes - Build scripts that toggle SENTRY_DISABLE_NATIVE_START at compile time - Test scripts to run auto and manual test suites separately - App start crash testing via flag file mechanism - TestControlModule to enable/disable crash-on-start from JS - Comprehensive E2E test documentation Unlike iOS which uses launch arguments at runtime, Android requires separate builds with different build configurations to control native initialization. Closes #4912 Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com> * fix(e2e): Add scrolling to find crash control buttons in Android test The crash control buttons are off-screen, so the Maestro flow needs to scroll to find them before tapping. This matches the pattern used in other Android E2E tests. Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com> * fix(e2e): Make Android crash flag auto-expire after one crash The crash flag file was persisting across app launches, causing the app to crash indefinitely. Now the flag auto-deletes when read, allowing: 1. First launch: Enable flag 2. Second launch: Read flag, delete it, then crash 3. Third launch: Start normally and send crash report This solves the chicken-and-egg problem where the app couldn't reach JavaScript to clear the flag because it kept crashing before JS loaded. Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com> * fix(e2e): Handle wrapped exceptions in Android crash test Android wraps exceptions thrown in Application.onCreate() with: "Unable to create application... RuntimeException: <original message>" Updated the test to check if ANY exception in the chain contains our intentional crash message, rather than expecting an exact match on the first exception. Test now passes locally and should pass in CI. Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com> * Clean up notes for now --------- Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

packages/core/android/src/main/java/io/sentry/react/RNSentryStart.java

# Conflicts: # samples/react-native/android/app/build.gradle

…ions Fixes a crash on Android startup when initializing from sentry.options.json without dsn or devServerUrl fields. The code was calling getString() on ReadableMap without checking if the keys exist first, which throws NoSuchKeyException for missing keys. Both fields are optional in configuration files, so the code now checks for key existence before accessing values, returning null when keys are missing. This matches the pattern used throughout the rest of the file and is already handled correctly by the null-checks in the breadcrumb filter logic. Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

## DESCRIBE YOUR PR *Tell us what you're changing and why. If your PR **resolves an issue**, please link it so it closes automatically.* ## IS YOUR CHANGE URGENT? Help us prioritize incoming PRs by letting us know when the change needs to go live. - [ ] Urgent deadline (GA date, etc.):  - [ ] Other deadline:  - [x] None: Not urgent, can wait up to 1 week+ After getsentry/sentry-react-native#5582 is released ## SLA - Teamwork makes the dream work, so please add a reviewer to your PRs. - Please give the docs team up to 1 week to review your PR unless you've added an urgent due date to it. Thanks in advance for your help! ## PRE-MERGE CHECKLIST *Make sure you've checked the following before merging your changes:* - [ ] Checked Vercel preview for correctness, including links - [ ] PR was reviewed and approved by any necessary SMEs (subject matter experts) - [ ] PR was reviewed and approved by a member of the [Sentry docs team](https://github.com/orgs/getsentry/teams/docs) ## LEGAL BOILERPLATE  Look, I get it. The entity doing business as "Sentry" was incorporated in the State of Delaware in 2015 as Functional Software, Inc. and is gonna need some rights from me in order to utilize my contributions in this here PR. So here's the deal: I retain all rights, title and interest in and to my contributions, and by keeping this boilerplate intact I confirm that Sentry can use, modify, copy, and redistribute my contributions, under Sentry's choice of terms. ## EXTRA RESOURCES - [Sentry Docs contributor guide](https://docs.sentry.io/contributing/)

krystofwoldrich and others added 30 commits January 21, 2025 17:22

ref(ios): Extract Cocoa SDK init into standalone file (#4442)

00e9040

Merge branch 'main' into capture-app-start-errors

4c0b8f4

feat(experimental): Add native startWithConfigureOptions for Apple …

7144a64

…platforms (#4444)

feat: Read sentry.options.json during cocoa init (#4447)

7850677

Adds utility class for converting JsonObject to WritableMap (#4479)

1e5dbde

* Convert json object to writable map * Make class/methods package-private(default)

feat: Automatically load sentry.options.json file (#4476)

22a5f81

feat(experimental): Initialize Android SDK from json configuration (#…

a1cb36d

…4451)

Merge branch 'main' into capture-app-start-errors

95c36ef

misc: Add sentry.options.json example to the changelog (#4509)

14fe05d

feat(init): Load options from sentry.options.json in JS (#4510)

15a7e6d

release: 6.7.0-alpha.0

b9ec093

Merge branch 'release/6.7.0-alpha.0' into capture-app-start-errors

dbdd4b5

misc(sample): Change RN Sample to use native file init by default (#4522

b947d7f

)

chore(sample-rn): Remove duplicate init options from code (#4532)

6b08b9a

chore(sample-rn): Always use fhe file option (including auto init) (#…

a7ffa1f

…4533)

internal(sample-rn): Add Detox for integration/e2e tests of the rn sa…

28cf7b4

…mple (#4535)

internal(sample-rn): Add header and message envelope tests (#4536)

cf00d4d

Merge remote-tracking branch 'origin/main' into capture-app-start-errors

b754aa3

fix(sample-e2e): Fix type errors missing sentry/core and afterAll (#4564

0bf6636

)

Merge remote-tracking branch 'origin/main' into capture-app-start-errors

0f5cd7d

chore(samples): Add package scripts for native builds, dsn and testing (

e935360

#4561)

Merge branch 'main' into capture-app-start-errors

952dd05

test(e2e): Verify captured Errors Screen transaction (#4584)

ae342a3

test(e2e): Add auto init from JS tests (#4588)

770f9fb

test(e2e): Add app start crash test for iOS (#4593)

cbb85b2

test(e2e): Avoid race conditions when waiting for captured message (#…

b4ee16b

…4595)

chore(sample-e2e): Move Detox related files to e2e-detox dir

ee11f58

Merge branch 'main' into capture-app-start-errors

588ba6d

Fix native ios tests

e6505b7

antonis mentioned this pull request Jan 27, 2026

test(e2e): Add auto init from JS tests for Android #5583

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antonis marked this pull request as ready for review January 27, 2026 09:41

antonis requested review from alwx and lucas-zimerman as code owners January 27, 2026 09:41

This was referenced Jan 27, 2026

feat: v7: Capture app start errors before JS #5470

Closed

RN: Capture Startup Crashes getsentry/sentry-docs#16170

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antonis and others added 2 commits January 27, 2026 14:05

Mark area

f4584c5

Co-authored-by: LucasZF <lucas-zimerman1@hotmail.com>

Merge branch 'v8' into antonis/capture-app-start-errors-v8

44282b5

# Conflicts: # CHANGELOG.md

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antonis mentioned this pull request Jan 27, 2026

fix(android): Fix ConcurrentModificationException #5588

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antonis and others added 2 commits January 29, 2026 14:39

Merge branch 'v8' into antonis/capture-app-start-errors-v8

8aa1902

# Conflicts: # samples/react-native/android/app/build.gradle

antonis merged commit d5c32e3 into v8 Jan 29, 2026
100 of 108 checks passed

antonis deleted the antonis/capture-app-start-errors-v8 branch January 29, 2026 15:26

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feat: v8: Capture app start errors before JS #5582

feat: v8: Capture app start errors before JS #5582

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📢 Type of change

📜 Description

Changes

Internal

Note

💡 Motivation and Context

💚 How did you test it?

📝 Checklist

🔮 Next steps

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iOS (new) Performance metrics 🚀

Baseline results on branch: v8

Startup times

App size

Previous results on branch: antonis/capture-app-start-errors-v8

Startup times

App size

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iOS (legacy) Performance metrics 🚀

Baseline results on branch: v8

Startup times

App size

Previous results on branch: antonis/capture-app-start-errors-v8

Startup times

App size

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