flutter analyze crashes with FormatException when project path contains non-ASCII characters (Flutter 3.47)

Description

flutter analyze crashes with an unhandled FormatException: Unexpected end of input in the analysis server's LSP channel when the project is located under a path containing non-ASCII characters (e.g. a curly apostrophe ’ in Alexander’s MacBook Pro).

dart analyze on the same project works fine.

Steps to reproduce

Create a directory with a non-ASCII character in its name, e.g. ~/Alexander’s/projects
cd into it and run flutter create repro
cd repro && flutter analyze

The same project copied to a pure-ASCII path analyzes without issues. Running via an ASCII symlink also fails, because the tool resolves the symlink back to the real (non-ASCII) path.

Expected result

flutter analyze completes normally regardless of path characters.

Actual result

The analysis server exits with code 255:

Unhandled exception:
FormatException: Unexpected end of input (at character 490)
...evenuoapp/"}],"capabilities":{"window":{"workDoneProgress":true}}
                                                                              ^
#0      _ChunkedJsonParser.fail (dart:convert-patch/convert_patch.dart:1466)
#1      _ChunkedJsonParser.close (dart:convert-patch/convert_patch.dart:496)
#6      LspByteStreamServerChannel._readMessage (package:analysis_server/src/lsp/channel/lsp_byte_stream_channel.dart:96)
...
analysis server exited with code 255

The truncated payload is the LSP initialize message whose rootUri contains the non-ASCII path. This looks like a Content-Length computed in characters rather than UTF-8 bytes somewhere in the flutter tool's LSP client, so the server reads fewer bytes than the actual message and JSON parsing hits end of input.

Environment

Flutter 3.47.0 stable (revision 4cf2416)
Dart 3.13.0
macOS 26.6.1 (arm64)

Regression note: this worked on Flutter 3.41.4 with the same project path.

@AlexanderVegazo26

@AlexanderVegazo26 Thanks for reporting this issue, I was able to reproduce it on my both machines mac & windows.

Confirming this as a regression. I downgraded to Flutter 3.41.4 to test, and flutter analyze runs without any issues there.

Findings:

Terminal logs macOS:

puneetkukreja@Puneets-MacBook-Air-2 ~ % cd google
puneetkukreja@Puneets-MacBook-Air-2 google % pwd
/Users/puneetkukreja/google
puneetkukreja@Puneets-MacBook-Air-2 google % mkdir "Puneet’s_repro"
puneetkukreja@Puneets-MacBook-Air-2 google % ls
issue_191167_app	Puneet’s_repro		splash_stable		vk_engine_churn_repro
puneetkukreja@Puneets-MacBook-Air-2 google % cd "Puneet’s_repro"
puneetkukreja@Puneets-MacBook-Air-2 Puneet’s_repro % flutter create repro_app
Developer identity "Apple Development: 917000180280 (62HY893DS7)" selected for iOS code signing
Creating project repro_app...
Resolving dependencies in `repro_app`... 
Downloading packages... 
Got dependencies in `repro_app`.
Wrote 131 files.

All done!
You can find general documentation for Flutter at: https://docs.flutter.dev/
Detailed API documentation is available at: https://api.flutter.dev/
If you prefer video documentation, consider: https://www.youtube.com/c/flutterdev

In order to run your application, type:

  $ cd repro_app
  $ flutter run

Your application code is in repro_app/lib/main.dart.

puneetkukreja@Puneets-MacBook-Air-2 Puneet’s_repro % cd repro_app 
puneetkukreja@Puneets-MacBook-Air-2 repro_app % flutter analyze
Unhandled exception:
FormatException: Unexpected end of input (at character 369)
...99s_repro/repro_app/"}],"capabilities":{"window":{"workDoneProgress":true}}
                                                                              ^

#0      _ChunkedJsonParser.fail (dart:convert-patch/convert_patch.dart:1466)
#1      _ChunkedJsonParser.close (dart:convert-patch/convert_patch.dart:496)
#2      _parseJson (dart:convert-patch/convert_patch.dart:36)
#3      JsonDecoder.convert (dart:convert/json.dart:640)
#4      JsonCodec.decode (dart:convert/json.dart:219)
#5      jsonDecode (dart:convert/json.dart:160)
#6      LspByteStreamServerChannel._readMessage (package:analysis_server/src/lsp/channel/lsp_byte_stream_channel.dart:96)
#7      LspByteStreamServerChannel.listen.<anonymous closure> (package:analysis_server/src/lsp/channel/lsp_byte_stream_channel.dart:67)
#8      _rootRunUnary (dart:async/zone_root.dart:48)
#9      _CustomZone.runUnary (dart:async/zone.dart:816)
#10     _CustomZone.runUnaryGuarded (dart:async/zone.dart:710)
#11     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:381)
#12     _DelayedData.perform (dart:async/stream_impl.dart:573)
#13     _PendingEvents.handleNext (dart:async/stream_impl.dart:678)
#14     _PendingEvents.schedule.<anonymous closure> (dart:async/stream_impl.dart:649)
#15     _rootRun (dart:async/zone_root.dart:27)
#16     _CustomZone.run (dart:async/zone.dart:810)
#17     _CustomZone.runGuarded (dart:async/zone.dart:702)
#18     _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:743)
#19     _rootRun (dart:async/zone_root.dart:35)
#20     _CustomZone.run (dart:async/zone.dart:810)
#21     _CustomZone.runGuarded (dart:async/zone.dart:702)
#22     _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:743)
#23     _microtaskLoop (dart:async/schedule_microtask.dart:40)
#24     _startMicrotaskLoop (dart:async/schedule_microtask.dart:49)
#25     _runPendingImmediateCallback (dart:isolate-patch/isolate_patch.dart:127)
#26     _RawReceivePort._handleMessage (dart:isolate-patch/isolate_patch.dart:193)
Analyzing repro_app...                                                  
analysis server exited with code 255 and output:
[stderr] #7      LspByteStreamServerChannel.listen.<anonymous closure> (package:analysis_server/src/lsp/channel/lsp_byte_stream_channel.dart:67)
[stderr] #8      _rootRunUnary (dart:async/zone_root.dart:48)
[stderr] #9      _CustomZone.runUnary (dart:async/zone.dart:816)
[stderr] #10     _CustomZone.runUnaryGuarded (dart:async/zone.dart:710)
[stderr] #11     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:381)
[stderr] #12     _DelayedData.perform (dart:async/stream_impl.dart:573)
[stderr] #13     _PendingEvents.handleNext (dart:async/stream_impl.dart:678)
[stderr] #14     _PendingEvents.schedule.<anonymous closure> (dart:async/stream_impl.dart:649)
[stderr] #15     _rootRun (dart:async/zone_root.dart:27)
[stderr] #16     _CustomZone.run (dart:async/zone.dart:810)
[stderr] #17     _CustomZone.runGuarded (dart:async/zone.dart:702)
[stderr] #18     _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:743)
[stderr] #19     _rootRun (dart:async/zone_root.dart:35)
[stderr] #20     _CustomZone.run (dart:async/zone.dart:810)
[stderr] #21     _CustomZone.runGuarded (dart:async/zone.dart:702)
[stderr] #22     _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:743)
[stderr] #23     _microtaskLoop (dart:async/schedule_microtask.dart:40)
[stderr] #24     _startMicrotaskLoop (dart:async/schedule_microtask.dart:49)
[stderr] #25     _runPendingImmediateCallback (dart:isolate-patch/isolate_patch.dart:127)
[stderr] #26     _RawReceivePort._handleMessage (dart:isolate-patch/isolate_patch.dart:193)
puneetkukreja@Puneets-MacBook-Air-2 repro_app % dart analyze
Analyzing repro_app...                 3.2s
No issues found!
puneetkukreja@Puneets-MacBook-Air-2 repro_app %

Flutter doctor -v:

puneetkukreja@Puneets-MacBook-Air-2 google % flutter doctor -v
[✓] Flutter (Channel stable, 3.47.0, on macOS 26.4.1 25E253 darwin-arm64, locale en-US) [766ms]
    • Flutter version 3.47.0 on channel stable at /Users/puneetkukreja/Developer/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 4cf2416426 (6 days ago), 2026-08-11 11:53:49 -0700
    • Engine revision 5f77625673
    • Dart version 3.13.0
    • DevTools version 2.60.0
    • Feature flags: enable-web, enable-linux-desktop, enable-macos-desktop, enable-windows-desktop, enable-android, enable-ios, cli-animations, enable-native-assets, enable-record-use,
      enable-swift-package-manager, omit-legacy-version-file, enable-lldb-debugging, enable-uiscene-migration

[✓] Android toolchain - develop for Android devices (Android SDK version 37.0.0-rc1) [10.8s]
    • Android SDK at /Users/puneetkukreja/Library/Android/sdk
    • Emulator version 37.1.11.0 (build_id 15917651) (CL:N/A)
    • Platform android-37.1, build-tools 37.0.0-rc1
    • Java binary at: /Library/Java/JavaVirtualMachines/jdk-17.jdk/Contents/Home/bin/java
      This JDK is specified in your Flutter configuration.
      To change the current JDK, run: `flutter config --jdk-dir="path/to/jdk"`.
    • Java version Java(TM) SE Runtime Environment (build 17.0.12+8-LTS-286)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 26.6) [1,397ms]
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 17F113
    • CocoaPods version 1.16.2

[✓] Chrome - develop for the web [7ms]
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Connected device (3 available) [7.8s]
    • moto g57 power (mobile) • ZN52278M76 • android-arm64  • Android 16 (API 36)
    • macOS (desktop)         • macos      • darwin-arm64   • macOS 26.4.1 25E253 darwin-arm64
    • Chrome (web)            • chrome     • web-javascript • Google Chrome 151.0.7922.138
    ! Error: Browsing on the local area network for Puneet’s iPhone. Ensure the device is unlocked and attached with a cable or associated with the same local area network as this Mac.
      The device must be opted into Developer Mode to connect wirelessly. (code -27)

[✓] Network resources [929ms]
    • All expected network resources are available.

• No issues found!

Confirming this as a regression. I downgraded to Flutter 3.41.4 to test, and flutter analyze runs without any issues there.

Terminal logs windows:

PS C:\Developer\flutter> flutter doctor -v
Checking Dart SDK version...
Downloading Dart SDK from Flutter engine e4b8dca3f1b4ede4c30371002441c88c12187ed6...
Expanding downloaded archive with PowerShell...
Building flutter tool...
Running pub upgrade...
Resolving dependencies... (1.6s)
Downloading packages...
Got dependencies.
Downloading package sky_engine...                                  622ms
Downloading package flutter_gpu...                                 327ms
Downloading flutter_patched_sdk tools...                         1,272ms
Downloading flutter_patched_sdk_product tools...                   575ms
Downloading windows-x64 tools...                                    4.7s
Downloading windows-x64/font-subset tools...                     2,182ms
[!] Flutter (Channel [user-branch], 3.41.4, on Microsoft Windows [Version 10.0.26200.9168], locale en-IN) [567ms]
    ! Flutter version 3.41.4 on channel [user-branch] at C:\Developer\flutter
      Currently on an unknown channel. Run `flutter channel` to switch to an official channel.
      If that doesn't fix the issue, reinstall Flutter by following instructions at https://flutter.dev/setup.
    ! Upstream repository unknown source is not a standard remote.
      Set environment variable "FLUTTER_GIT_URL" to unknown source to dismiss this error.
    • Framework revision ff37bef603 (6 months ago), 2026-03-03 16:03:22 -0800
    • Engine revision e4b8dca3f1
    • Dart version 3.11.1
    • DevTools version 2.54.1
    • Feature flags: enable-web, enable-linux-desktop, enable-macos-desktop, enable-windows-desktop, enable-android, enable-ios,
      cli-animations, enable-native-assets, omit-legacy-version-file, enable-windowing, enable-lldb-debugging,
      enable-uiscene-migration
    • If those were intentional, you can disregard the above warnings; however it is recommended to use "git" directly to perform
      update checks and upgrades.

[√] Windows Version (Windows 11 or higher, 25H2, 2009) [2.7s]

[√] Android toolchain - develop for Android devices (Android SDK version 37.0.0) [4.6s]
    • Android SDK at C:\Users\Puneet\AppData\Local\Android\sdk
    • Emulator version 36.6.11.0 (build_id 15507667) (CL:N/A)
    • Platform android-37.1, build-tools 37.0.0
    • Java binary at: C:\Program Files\Android\Android Studio1\jbr\bin\java
      This is the JDK bundled with the latest Android Studio installation on this machine.
      To manually set the JDK path, use: `flutter config --jdk-dir="path/to/jdk"`.
    • Java version OpenJDK Runtime Environment (build 21.0.10+-14961533-b1163.108)
    • All Android licenses accepted.

[√] Chrome - develop for the web [207ms]
    • Chrome at C:\Program Files\Google\Chrome\Application\chrome.exe

[√] Visual Studio - develop Windows apps (Visual Studio Community 2026 18.3.2) [204ms]
    • Visual Studio at C:\Program Files\Microsoft Visual Studio\18\Community
    • Visual Studio Community 2026 version 18.3.11520.95
    • Windows 10 SDK version 10.0.26100.0

[√] Connected device (3 available) [422ms]
    • Windows (desktop) • windows • windows-x64    • Microsoft Windows [Version 10.0.26200.9168]
    • Chrome (web)      • chrome  • web-javascript • Google Chrome 151.0.7922.138
    • Edge (web)        • edge    • web-javascript • Microsoft Edge 151.0.4129.93

[√] Network resources [1,250ms]
    • All expected network resources are available.

! Doctor found issues in 1 category.
PS C:\Developer\flutter> cd ..
PS C:\Developer> cd ..
PS C:\> mkdir "C:\test_’_dir"


    Directory: C:\


Mode                 LastWriteTime         Length Name
----                 -------------         ------ ----
d-----        19-08-2026     07:36                test_’_dir


PS C:\> cd "C:\test_’_dir"
PS C:\test_’_dir> flutter create repro_app
Creating project repro_app...
Resolving dependencies in `repro_app`...
Downloading packages...
Got dependencies in `repro_app`.
Wrote 131 files.

All done!
You can find general documentation for Flutter at: https://docs.flutter.dev/
Detailed API documentation is available at: https://api.flutter.dev/
If you prefer video documentation, consider: https://www.youtube.com/c/flutterdev

In order to run your application, type:

  $ cd repro_app
  $ flutter run

Your application code is in repro_app\lib\main.dart.

PS C:\test_’_dir> cd .\repro_app\
PS C:\test_’_dir\repro_app> flutter analyze
Analyzing repro_app...
No issues found! (ran in 60.1s)
PS C:\test_’_dir\repro_app>

[flutter_tools] Compute LSP Content-Length header using UTF-8 byte le…

This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.

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flutter analyze crashes with FormatException when project path contains non-ASCII characters (Flutter 3.47) #191309

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flutter analyze crashes with FormatException when project path contains non-ASCII characters (Flutter 3.47) #191309

Description

Description

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Expected result

Actual result

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puneetkukreja98 commented on Aug 19, 2026

Findings:

puneetkukreja98 commented on Aug 19, 2026

github-actions commented on Sep 3, 2026

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