Flutter iOS Simulator (iOS 18.4) DevFSException: Failed to start Dart Development Service

Environment:

• Flutter SDK: 3.29.3 • channel stable • Dart 3.7.2 • DevTools 2.42.3
• Xcode: 16.3 (16E140) with Command Line Tools at /Applications/Xcode.app/Contents/Developer
• iOS Simulator: iPhone 16 Pro Max • iOS 18.4 runtime (UUID CAD7C59B-…)
• macOS: 15.4.1 (24E263)

Problem: When launching my Flutter app on the iOS 18.4 simulator in debug mode, the build succeeds but the Dart Development Service (DDS) never starts and the app never attaches. I see:

Warning: Failed to start DDS: Failed to start Dart Development Service  
DevFSException(Service disconnected, _createDevFS: (112) Service has disappeared, null)  
Error connecting to the service protocol: DartDevelopmentServiceException: Failed to start Dart Development Service

Steps to Reproduce:

1. git clone <your_repo_url> && cd <project>
2. flutter clean
3. rm -rf ~/Library/Developer/Xcode/DerivedData
4. cd ios && pod install && cd ..
5. flutter run --verbose -d CAD7C59B-8D46-4CAF-9437-AAC75E0D24FE

Log Snippet:

<
[   +3 ms] executing: /usr/bin/arch -arm64e xcrun simctl launch CAD7C59B-8D46-4CAF-9437-AAC75E0D24FE com.example.mlbbHeroCalc --enable-dart-profiling --enable-checked-mode --verify-entry-points
[ +493 ms] com.example.mlbbHeroCalc: 57023
[   +1 ms] Waiting for VM Service port to be available...
[+8751 ms] VM Service URL on device: http://127.0.0.1:59733/qeivRY9V9ck=/
[   +7 ms] Caching compiled dill
[ +162 ms] Connecting to service protocol: http://127.0.0.1:59733/qeivRY9V9ck=/
[ +222 ms] Launching a Dart Developer Service (DDS) instance at http://127.0.0.1:0, connecting to VM service at http://127.0.0.1:59733/qeivRY9V9ck=/.
[ +311 ms] Warning: Failed to start DDS: Failed to start Dart Development Service
[        ] Fail to connect to service protocol: http://127.0.0.1:59733/qeivRY9V9ck=/: DartDevelopmentServiceException: Failed to start Dart Development Service
[        ] Error connecting to the service protocol: failed to connect to http://127.0.0.1:59733/qeivRY9V9ck=/ DartDevelopmentServiceException: Failed to start Dart Development Service
[   +2 ms] "flutter run" took 36.014ms.
[  +44 ms] 
           #0      throwToolExit (package:flutter_tools/src/base/common.dart:34:3)
           #1      RunCommand.runCommand (package:flutter_tools/src/commands/run.dart:931:9)
           <asynchronous suspension>
           #2      FlutterCommand.run.<anonymous closure> (package:flutter_tools/src/runner/flutter_command.dart:1558:27)
           <asynchronous suspension>
           #3      AppContext.run.<anonymous closure> (package:flutter_tools/src/base/context.dart:154:19)
           <asynchronous suspension>
           #4      CommandRunner.runCommand (package:args/command_runner.dart:212:13)
           <asynchronous suspension>
           #5      FlutterCommandRunner.runCommand.<anonymous closure> (package:flutter_tools/src/runner/flutter_command_runner.dart:496:9)
           <asynchronous suspension>
           #6      AppContext.run.<anonymous closure> (package:flutter_tools/src/base/context.dart:154:19)
           <asynchronous suspension>
           #7      FlutterCommandRunner.runCommand (package:flutter_tools/src/runner/flutter_command_runner.dart:431:5)
           <asynchronous suspension>
           #8      run.<anonymous closure>.<anonymous closure> (package:flutter_tools/runner.dart:98:11)
           <asynchronous suspension>
           #9      AppContext.run.<anonymous closure> (package:flutter_tools/src/base/context.dart:154:19)
           <asynchronous suspension>
           #10     main (package:flutter_tools/executable.dart:99:3)
           <asynchronous suspension>


[        ] Running 3 shutdown hooks
[   +2 ms] Shutdown hooks complete
[ +261 ms] exiting with code 2
>

Full verbose log available here: https://gist.github.com/AkgulMuhammed/a9ee6cdb85b9e06e6ab38957411c89fe

Relevant Configuration:

# pubspec.yaml
dependencies:
  flutter:
    sdk: flutter
  permission_handler: ^12.0.0
  google_mlkit_text_recognition: ^0.15.0
  # … other plugins …

# ios/Podfile
platform :ios, '15.5'
use_frameworks!
target 'Runner' do
  pod 'permission_handler_apple', '12.0.0'
  # … other pods …
end

<!-- ios/Runner/Info.plist -->
<key>MinimumOSVersion</key>
<string>15.6</string>
<key>NSLocalNetworkUsageDescription</key>
<string>Allow Flutter tools on your computer to connect and debug your application.</string>

What I’ve Tried:

• flutter clean, DerivedData silme, pod install
• flutter run --no-dds (DDS still fails)
• Simulator “Erase All Content and Settings”
• Profile/Release mode (app launches, but debug still fails)
• Confirm no port conflicts or multiple sessions
• flutter doctor -v shows no issues

Expected vs Actual:

• Expected: App launches on simulator, connects to VM Service, hot reload works.
• Actual: DDS fails, DevFSException and DartDevelopmentServiceException appear.

Additional Context: This seems related to known DDS startup bugs on Flutter 3.29.x with iOS 18.4 simulator. Any workaround or fix pointers would be appreciated!