Error: Not found: 'dart:ui' when trying to run a Flutter project

Trying to run a Flutter project in VS Code yields many errors like this: Error: Not found: 'dart:ui'.

From looking at other issues (#2038, #1827) I understand that this is caused by trying to run a Dart project rather than a Flutter project. Well, I believe this is not the case in my project since the status bar does show Flutter and its version, in addition to selection of an emulator. The doctor also reports no issues whatsoever.

To Reproduce

I cannot share my code with the community (closed source), but the project opens and runs fine in both Android Studio and IntelliJ IDEA. The top-level directory contains a pubspec.yaml with a line reading sdk: "flutter".

Expected behavior
The project runs as a Flutter project.

Screenshots

Versions (please complete the following information):

VS Code version: 1.64.2
Dart extension version: 3.34.0
Dart/Flutter SDK version: Flutter 2.11.0-0.0.pre.582 • channel master • Dart 2.17.0 (build 2.17.0-105.0.dev)

Are you able to make a small project in the same structure that triggers this that you can share?

Could you try capturing debugging logs while reproducing this?

Run the Dart: Capture Debugging Logs command
Reproduce the issue
Click Cancel on the logging notification to stop logging and open the log
Remove anything sensitive from the log
Attach the log here (or in a gist)

Thanks!

From the log: [9:12:04 AM] [General] [Info] Project (/path/to/workspace/app/lib/googledevel.dart) not recognised as Flutter or Web, will use Dart debugger. I don't get why it's not being detected as Flutter, when 5 other subdirectories alongside it (admin, core, ui, ui_mobile, db) are detected as Flutter projects.

The structure of the workspace:

/path/to/workspace
|__ project.code-workspace
|__ admin/
|     |__ pubspec.yaml
|     |__ lib/
|__ app/
|     |__ pubspec.yaml
|     |__ lib/
|__ core/
|     |__ pubspec.yaml
|     |__ lib/
|__ db/
|     |__ pubspec.yaml
|     |__ lib/
|__ ui/
|     |__ pubspec.yaml
|     |__ lib/
|__ ui_mobile/
      |__ pubspec.yaml
      |__ lib/

All of them are Flutter projects. Only the app/ subdirectory is not detected as a Flutter project... I'm baffled.

.vscode/launch.json looks like so:

{
  "configurations": [
    {
      "name": "App (Devel)",
      "type": "dart",
      "request": "launch",
      "cwd": "app/",
      "program": "lib/googledevel.dart",
      "args": [
        "--no-sound-null-safety",
        "--enable-experiment=non-nullable",
        "--enable-experiment=nonfunction-type-aliases",
        "--enable-experiment=constructor-tearoffs"
      ]
    }
  ]
}

[9:12:04 AM] [General] [Info] Project (/path/to/workspace/app/lib/googledevel.dart) not recognised as Flutter or Web, will use Dart debugger

Are you able to share the log (here or emailing me at [email protected])? The path there is supposed to be a project folder, so having lib/googledevel.dart on the end looks odd. Could you also share the pubspec.yaml for the app project?

Sorry, I was mistaken - we log the program not the project folder. But we use the debugConfig.cwd to check for Flutter:

Dart-Code/src/extension/providers/debug_config_provider.ts

Line 315 in 2f9483a

    
           if (isFlutterProjectFolder(debugConfig.cwd) || this.wsContext.config.forceFlutterDebug) {

The detection of the SDK is a regex, so if your formatting is different here, perhaps that would do it:

Dart-Code/src/extension/sdk/utils.ts

Lines 430 to 436 in 2f9483a

    
           export function referencesFlutterSdk(folder?: string): boolean { 
        
           	if (folder && hasPubspec(folder)) { 
        
           		const regex = new RegExp("sdk\\s*:\\s*flutter", "i"); 
        
           		return regex.test(fs.readFileSync(path.join(folder, "pubspec.yaml")).toString()); 
        
           	} 
        
           	return false; 
        
           }

[9:12:04 AM] [General] [Info] Project (/path/to/workspace/app/lib/googledevel.dart) not recognised as Flutter or Web, will use Dart debugger

Are you able to share the log (here or emailing me at [email protected])? The path there is supposed to be a project folder, so having lib/googledevel.dart on the end looks odd. Could you also share the pubspec.yaml for the app project?

Basically, I specify a different template file to run (flutter run -t ...) and that's what you saw there, the lib/googledevel.dart). I referred to it earlier as lib/devel.dart mistakenly.

Anyway, I sent you the log to: [email protected].

app/pubspec.yaml (strippe down) is below:

name: "flutter_app"
publish_to: "none"
version: "1.0.0"

environment:
  sdk: ">=2.16.0 <3.0.0"
  flutter: ">=2.10.0"

dependencies:
  # List of all deps comes here...

  flutter:
    sdk: "flutter"

  flutter_localizations:
    sdk: "flutter"

dev_dependencies:
  analyzer: "3.2.0"
  build_runner: "2.1.7"
  flutter_lints: "1.0.4"

flutter:
  generate: true
  uses-material-design: false
  assets:
    - "res/"

Thanks! At a glance, I think it's because of the quotes in sdk: "flutter". I'll improve the regex to handle these better, but if you can remove them in the meantime it should solve your issue.

Thanks! At a glance, I think it's because of the quotes in sdk: "flutter". I'll improve the regex to handle these better, but if you can remove them in the meantime it should solve your issue.

Trying... Yup, this seems to have fixed the problem.

It's great that you uncovered the reason! You should probably check for single- and double-quotes as well.

@clebemachado You can't use dart:ui in Dart projects, as it's part of Flutter - see dart-lang/sdk#50854 (comment).

@DanTup

@DanTup hi , I still have the same problem
could you plz help me
`
name: projectName
description: A new Flutter project.

publish_to: 'none'

version: 1.0.0+1

environment:
sdk: '>=3.0.6 <4.0.0'

dependencies:
flutter:
sdk: flutter
cupertino_icons: ^1.0.2

dev_dependencies:
flutter_test:
sdk: flutter

flutter_lints: ^2.0.0

flutter:

uses-material-design: true
`

@deemKhlaed

@deemKhlaed please file a new issue and include a screenshot of exactly what you're seeing, and details of how you are running the application. Thanks!

/C:/flutter/packages/flutter/lib/src/material/arc.dart:6:8: Error: Dart library 'dart:ui' is not available on this platform.
import 'dart:ui' show lerpDouble;

Please suggest the answer

@nitinyeranale

@nitinyeranale please file a new issue and include a full VS Code screenshot of exactly what you're seeing, and details of how you are running the application. Thanks!

Hi Mr.
I add my problem as a ss.
when I run my code by the f5 button problem it works but i couldn't run it from the terminal as seen on SS by writing " dart lib/main.dart "
It's not a problem for now but I feel it going to in further steps.

but i couldn't run it from the terminal as seen on SS by writing " dart lib/main.dart "

This is expected behaviour. Flutter apps are run with flutter run not dart. Only Dart (non-Flutter) apps can be run with dart.

I would recommend using F5/Ctrl+F5 in VS Code though, as you'll get more functionality (such as the debugger) compared to running from the terminal.

@DanTup

Thank you Mr @DanTup . Your response speed is incredible.

Basically i have issues but i think my problem is my friend give code source which has old version of dart and flutter than i have on my pc so that's cause problem in pubspec.yaml but when i do any change in yaml folder ,the code won't execute like i don't which line attributes that i should change (sorry for my bad english)

@Boutheinaikram I don't think an old version of Dart/Flutter should cause this error, but please open a new issue with a screenshot showing all of VS Code and any error messages so I can take a look. Thanks!

@Boutheinaikram I don't think an old version of Dart/Flutter should cause this error, but please open a new issue with a screenshot showing all of VS Code and any error messages so I can take a look. Thanks!

here's all the screenshot of all errors and output thanks in advance

@Boutheinaikram based on the screenshot, I think you may be running using the Code Runner extension? See my comment above at #3834 (comment)

The Code Runner extension does not understand Flutter and will try to run Flutter apps using dart instead of flutter. I would recommend disabling the Code Runner extension in any Dart/Flutter workspaces and using the options from the Dart/Flutter extensions instead.

There's an issue at formulahendry/vscode-code-runner#674 asking for Code Runner to hides it buttons for Dart/Flutter but it unfortunately has not received any response.

i try all ur step but the problem is same and actualy i use android studio to execute ,my friend coded the app in an older version of Dart (3.3.0), and it worked perfectly. However her pc broke, so she transferred her app to my pc. I installed the latest version of dart (3.4.0) and flutter (3.2.0). When I tried to execute it in Android Studio, it didn't work because there was a problem with dart:ui. I thought the issue might be due to the code not being compatible with the versions I have on my pc. So
I tried to modify the pubspec.yaml file because it had sdk: '>=2.19.6 <3.0.0'. I changed it to sdk: '>=3.0.6 <4.0.0', but it still didn't work. I made sure that the path is correct and everything is clear, but I still don't know where the problem is. here's the error in android studio

@Boutheinaikram the error in your latest screenshot is a different error.

The error shown in your earlier post from VS Code looks like a problem caused by using Code Runner (or something else that's using dart to run a Flutter app).

The error in your latest screenshot is indeed because of version changes - the code is trying to use ThemeData.backgroundColor but that was deprecated in Flutter 3.3 and removed in Flutter 3.19. You will need to update the code to make it compatible with the latest versions of Flutter or switch back to an older Flutter SDK. You might be able to use dart fix to update some of these (see https://docs.flutter.dev/tools/flutter-fix).

There are a number of places listed at https://flutter.dev/community#community-grid that may be better suited for general Flutter coding questions/help.

Make detection of Flutter projects tolerate quotes in pubspec

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Error: Not found: 'dart:ui' when trying to run a Flutter project #3834

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	export function referencesFlutterSdk(folder?: string): boolean {
	if (folder && hasPubspec(folder)) {
	const regex = new RegExp("sdk\\s:\\sflutter", "i");
	return regex.test(fs.readFileSync(path.join(folder, "pubspec.yaml")).toString());
	}
	return false;
	}

Error: Not found: 'dart:ui' when trying to run a Flutter project #3834

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DanTup commented on Feb 17, 2022

noordawod commented on Feb 17, 2022

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DanTup commented on Feb 17, 2022

DanTup commented on Feb 17, 2022

noordawod commented on Feb 17, 2022

noordawod commented on Feb 17, 2022

DanTup commented on Feb 17, 2022

noordawod commented on Feb 17, 2022

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DanTup commented on May 27, 2023

deemKhlaed commented on Aug 2, 2023

DanTup commented on Aug 2, 2023

nitinyeranale commented on Oct 19, 2023

DanTup commented on Oct 19, 2023

YusufBabali commented on Feb 9, 2024

DanTup commented on Feb 9, 2024

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bth-ik commented on May 21, 2024

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DanTup commented on May 22, 2024

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