dart-lang / dart-lang/webdev

Dart Debug Extension on Chrome stopped working after Flutter 3.32.0 and Dart 3.8.0 update

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dart-debug-extension
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Dart
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Description

After updating Flutter to version 3.32.0 and Dart to 3.8.0 stable, the Dart debug extension in Chrome no longer works when running Flutter web apps.

## Environment:
Flutter: 3.32.0 (stable)
Dart: 3.8.0 (stable) (Wed May 14 09:07:14 2025 -0700) on macos_arm64
OS: macOS 15.5 (Build 24F74)
Chrome: Version 136.0.7103.114 (Official Build) (arm64)
VS Code: 1.99.3 and 1.100.0-insider

Flutter Doctor Summary:
`[✓] Flutter (Channel stable, 3.32.0, on macOS 15.5 24F74 darwin-arm64, locale en-US)
[✓] Android toolchain - Android SDK 34.0.0
[!] Xcode - issues noted (Simulator not installed, CocoaPods outdated)
[✓] Chrome - develop for the web
[✓] Android Studio 2025.1.2
[✓] VS Code versions 1.99.3 & 1.100.0-insider
[✓] Connected devices (2 available)
`

# Reproduction Steps: Running a Sample Flutter App on Web (Web Server)
Update Flutter to 3.32.0 and Dart to 3.8.0

## 1. Create a New Flutter App
```zsh
flutter create sample_app
cd sample_app
```

## 2. Run the App on Web Using Web Server (Port 7456)
```zsh
flutter run -d web-server --web-port=7456
```

## 3. Access the App in Your Browser
- Open your browser and navigate to:
`http://localhost:7456`

## 5. Expected Result
- The Flutter counter app should load in your browser, served by the Flutter web server on port 7456.
- The Dart Debug extension in chrome should automatically activate, and allowing user to continue with development properly.

## 6. Current Result
- The Dart Debug extension does **not** activate when running with the web server, so debugging features are unavailable.

Run Flutter web app using:
`flutter run -d web-server --web-hostname localhost --web-port 7357
`
Attempt to debug using Dart Debug extension on Chrome

Observe debug extension is disabled in extensions, so failing to attach or respond

Expected Behavior:
Dart Debug extension should work as before (not disabled) and attach to the running Flutter web app for debugging.

Actual Behavior:
Dart Debug extension fails to function after update.

![Image](https://github.com/user-attachments/assets/937bf1f4-46d8-4e5a-924f-c792e1d7823b)

Contributor guide

Open the contributing guide

Research direction

Reproduce the issue with `flutter run -d web-server --web-hostname localhost --web-port 7357` using Flutter 3.32.0 and Dart 3.8.0, then inspect how the Chrome Dart Debug extension attaches to the web-server output. Done means the extension remains enabled, activates, and attaches to the running Flutter web app for debugging.

Written by the indexing model from the issue text.

Assessment

Tech stack
dart
Domain
tooling, web-dev
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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