Unbalanced calls start/end for tag 20 (and tag 19)

[chrisnojima]

Description

Hi,

I was debugging an issue where I see crashes in the RCTPerformanceLogger in - (void)markStopForTag:(RCTPLTag)tag in my iOS app.

I noticed I saw logs for

Unbalanced calls start/end for tag 20
Unbalanced calls start/end for tag 19

After debugging this for awhile I started up a clean project using react-native-cli and it also exhibits this behavior

I cannot see in the ios code where we ever attempt to markStartForTag with RCTPLAppStartup or
RCTPLInitReactRuntime

Steps to reproduce

1. npx @react-native-community/cli@latest init AwesomeProject
2. Build and run
3. Look at console

React Native Version

0.83.1 (also in 0.79.3 etc)

Affected Platforms

Runtime - iOS

Output of npx @react-native-community/cli info

Fetching system and libraries information...
System:
  OS: macOS 15.6.1
  CPU: (16) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
  Memory: 38.34 MB / 16.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 24.5.0
    path: /usr/local/bin/node
  Yarn:
    version: 1.22.22
    path: /usr/local/bin/yarn
  npm:
    version: 11.5.1
    path: /usr/local/bin/npm
  Watchman:
    version: 2025.08.25.00
    path: /usr/local/bin/watchman
Managers:
  CocoaPods:
    version: 1.16.2
    path: /usr/local/bin/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 25.0
      - iOS 26.0
      - macOS 26.0
      - tvOS 26.0
      - visionOS 26.0
      - watchOS 26.0
  Android SDK:
    API Levels:
      - "33"
      - "35"
    Build Tools:
      - 30.0.3
      - 33.0.0
      - 35.0.0
      - 36.0.0
    Android NDK: 26.1.10909125
IDEs:
  Android Studio: 2025.1 AI-251.26094.121.2513.14007798
  Xcode:
    version: 26.0/17A324
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 17.0.16
    path: /usr/bin/javac
  Ruby:
    version: 2.6.10
    path: /usr/bin/ruby
npmPackages:
  "@react-native-community/cli":
    installed: 20.0.0
    wanted: 20.0.0
  react:
    installed: 19.1.0
    wanted: 19.1.0
  react-native:
    installed: 0.81.4
    wanted: 0.81.4
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: true
iOS:
  hermesEnabled: true
  newArchEnabled: true

Stacktrace or Logs

/Users/chrisnojima/code/cleanrn/AwesomeProject/node_modules/react-native/ReactCommon/react/runtime/ReactInstance.cpp
      ReactMarker::logMarkerBridgeless(ReactMarker::APP_STARTUP_STOP);

MANDATORY Reproducer

https://github.com/react-native-community/reproducer-react-native

Screenshots and Videos

No response

[react-native-bot]

Warning

Missing reproducer: We could not detect a reproducible example in your issue report. Reproducers are mandatory and we can accept only one of those as a valid reproducer:

• For majority of bugs: send us a Pull Request with the RNTesterPlayground.js edited to reproduce your bug.
• If your bug is UI related: a Snack
• If your bug is build/upgrade related: a project using our Reproducer Template

You can read more about about it on our website: How to report a bug.

[chrisnojima]

#53821

[cortinico]

Unbalanced calls start/end for tag 20
Unbalanced calls start/end for tag 19

Are you saying that this is happening in any freshly created app?

[chrisnojima]

Thats what I see. I made a new folder, made a vanilla app using the template and run it in xcode and i see the log

[chrisnojima]

I also see it in random logs in other issues (unrelated but its in peoples logs)

[chrisnojima]

#42999
#46203
#47010
#48031 etc

[cortinico]

#42999 #46203 #47010 #48031 etc

Those are all from 1+ year ago though. Anything more recent that could exclude an error from your environment?

[chrisnojima]

I don't think there's anything special about my environment. Is there some output you want me to look at? I see this in my users logs so its not something in my local runtime. I see it on device and sim.

Looking in issues here this #49323 is from Feb 11
#48403 is from december