Flutter : Target file "lib/main.dart" not found

Question

When I perform a flutter run I get an error

Target file "lib/main.dart" not found.

Why is this happening and how can I fix this ?

What directory do you execute the command from. Please add the output of flutter doctor to your question. — Günter Zöchbauer
– Günter Zöchbauer, Commented May 25, 2018 at 6:02

starball · Accepted Answer · 2022-12-25 21:01:30Z

115

You can run any file from any DIR provided that you set the target file path, example:

flutter run -t lib/main_dev.dart

OR

flutter run lib/dev/main_dev.dart

UPDATE (2020 February 5th)

It is however not advisable to remove main.dart from your project.

I'm sure most of you found this link because you are setting up / configuring your app to accommodate for different environments e.g. dev, stg, beta and prod.

Example:

main_dev.dart:

void main() async {
  dynamic configuredApp = AppConfig(
    appName: 'Flutter',
    flavorName: 'development',
    appVersion: 1.0,
    apiBaseUrl: 'https://dev-api.example.com/'
  );

  runApp(App(configuredApp));
}

main.dart

class App extends StatefulWidget {
  final dynamic configuredApp;

  App(this.configuredApp);

  @override
  _AppState createState() => _AppState();
}

As it turns out some build steps will fail in Android Studio mostly Gradle related if you don't have a main.dart file and method main() {} referenced inside this file.

Common build errors (AndroidX migrate, APK build etc.)
More info / solutions below related to flutter build error: finished with non-zero exit value 1

An alternative to flutter run -t lib/main_dev.dart in VS Code with the debugger tool.

Click "Add Configuration" and add the following or add manually:

.vscode/launch.json

  "configurations": [

    {
      "name": "Flutter",
      "request": "launch",
      "type": "dart",
      // "args": ["--enable-software-rendering"]
      // "flutterMode": "profile", //debug //release 
      "program": "${workspaceFolder}/lib/main_dev.dart"
    }
  ]

edited Dec 25, 2022 at 21:01

starball♦

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answered Oct 26, 2018 at 7:20

Elroy

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4 Comments

atereshkov Over a year ago

Yep, it's working as expected. Thanks! flutter build apk lib/config/env_dev.dart

Naman Jain Over a year ago

the second part is the best answer

Moxet Jan Over a year ago

this works very well, i did with manual path.

Rafsan Uddin Beg Rizan Over a year ago

If some one having issue file not found. Change to this "program": "./lib/staging_main.dart".

iDecode · Accepted Answer · 2020-11-11 12:24:43Z

17

Flutter is looking for main.dart in lib folder while you must have had file inside any other package.

Best solution is to place your main.dart file just inside lib folder. Flutter run command will work then for sure.

It worked for me.

main.dart url should be:

<app dir>/lib/main.dart

edited Nov 11, 2020 at 12:24

iDecode

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answered Jun 15, 2018 at 7:56

Munish Thakur

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1 Comment

Rachit Rawat Over a year ago

What if it's in another location? since i am using different files to build my prod and dev environment.

Shubhral · Accepted Answer · 2020-08-26 07:50:00Z

So basically when you execute this

 flutter run

Flutter tries to find main.dart in /lib directory.

So if you have a file that is present in some other child directory of /lib directory or has a different name like result_page.dart, you'd encounter this error. Now, a lot of answers had suggested to either rename your file to main.dart or move it directly under /lib directory.

But you can actually simply run any file by simply providing the target file's path from the current directory like this -

flutter run --target=lib/customization/result_screen.dart

So this would simply execute my result_screen.dart file present under some other child directory called customization.

You can also generate the APK file following the same logic and the command would look like this -

flutter build apk --target=lib/customization/result_screen.dart --target-platform=android-arm64

where --target-platform=android-arm64 is optional and is meant for 64-bit Android devices which helps in reducing APK size which otherwise would generate a fat APK including both 32-bit and 64-bit binaries. More info here

NewbieCoder · Accepted Answer · 2018-12-30 23:28:23Z

3

If you are using vscode...

When the error occurs, the vscode folder occurs in the side bar. It has the launch.json file inside.

You can change the "program": "..." property in the launch.json file to run the .dart file in the directory where you want.

answered Dec 30, 2018 at 23:28

NewbieCoder

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Comments

Steve Lukis · Accepted Answer · 2019-01-21 03:53:59Z

3

This happened when I used Visual Studio Code. What I did to fix the problem was by editing the .vscode/launch.json file and change the value of "program" to the absolute path of my main.dart file (e.g. C://...).

answered Jan 21, 2019 at 3:53

Steve Lukis

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Comments

m02ph3u5 · Accepted Answer · 2019-11-17 20:03:00Z

3

If you are using VSCODE

Check folder .vscode>launch.json and add configuration:
if you have it already change a "program": "path of main.dart example: lib/main.dart"

 {
    "name": "Dart",
    "type": "dart",
    "request": "launch",
    "program": "lib/main.dart"
},

edited Nov 17, 2019 at 20:03

m02ph3u5

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answered Nov 17, 2019 at 19:44

Aminjoni Abdullozoda

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Comments

Mina Farid · Accepted Answer · 2021-07-20 01:09:07Z

3

Make Sure that your main.dart inside lib folder directly not in another package or directory

answered Jul 20, 2021 at 1:09

Mina Farid

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Comments

Kefa Mutinda · Accepted Answer · 2019-04-03 18:26:56Z

2

If you are using visual code and you encounter this problem while debugging, just go to launch.json, go to the location of where your flutter app is located, to the lib folder and then to the main.dart ,copy the path then add it to the text program in the launch.json as indicated on the photo below

launch.json "program" path

answered Apr 3, 2019 at 18:26

Kefa Mutinda

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Comments

Zaid Pathan · Accepted Answer · 2020-11-11 12:29:38Z

2

If you are having multiple iOS schemes then you could try like this:

flutter run --flavor UserDev -t lib/user/dev/main_dev.dart

For,

"configurations": [{
            "name": "User-Dev",
            "request": "launch",
            "type": "dart",
            "program": "lib/user/dev/main_dev.dart",
            "args": [
                "--flavor",
                "UserDev"
            ]
        }]

answered Nov 11, 2020 at 12:29

Zaid Pathan

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Comments

adiga · Accepted Answer · 2019-07-01 12:40:33Z

1

in android studio this wokrs for me

left click in main.dart
right click in profile main.dart

this executes an snapshot aplicaction to configure the root profile a run your app

enter image description here

edited Jul 1, 2019 at 12:40

adiga

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answered Jul 1, 2019 at 12:32

Robinson Calderón

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Comments

Salah Qamachi · Accepted Answer · 2021-06-08 18:13:04Z

1

I had a similar error message, and it happened because I accidentally deleted the void main()

answered Jun 8, 2021 at 18:13

Salah Qamachi

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1 Comment

Eric Aya Over a year ago

Similar to stackoverflow.com/a/58618151/2227743

Sukhi · Accepted Answer · 2019-04-08 06:44:42Z

0

VSCode Users: Plese navigate to launch.json and replace the "Program" line with the following :

"Program":"${rootProject.buildDir}/${project.name}/lib/main.dart"

answered Apr 8, 2019 at 6:44

Sukhi

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Comments

Mehmet Bütün · Accepted Answer · 2019-08-28 21:33:42Z

0

If you are using the Debug Mode in vs code, ensure that the vs code working folder is your Flutter project main folder.

If you want to change the vs code working folder, you can use the File > Open Folder menu or Ctrl+O shortcut.

When I change the folder, It worked for me.

edited Aug 28, 2019 at 21:33

answered Aug 28, 2019 at 21:14

Mehmet Bütün

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Comments

champion-runner · Accepted Answer · 2019-10-30 04:50:20Z

0

Try final FlutterDevice flutterDevice = await FlutterDevice.create

The root cause is that the ResidentRunner we use to attach and do hot reloads will try to find a main.dart file when a target isn't announced. Attach doesn't provide a target, so it uses the default behavior always. As per DaceShuckerow.

This issue is still there on the official Repo.

answered Oct 30, 2019 at 4:50

champion-runner

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Comments

SanjaySingh · Accepted Answer · 2019-10-31 18:06:24Z

0

What my case was I forgot to write code for calling main....

void main()
{
  runApp......
}

And doing this worked

edited Oct 31, 2019 at 18:06

answered Oct 30, 2019 at 3:00

SanjaySingh

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1 Comment

Yunnosch Over a year ago

I helped with the formatting of your post. Please double check yourself the suspicious "Void" vs "void", because I am not so sure of the actual syntax in this technology. edit in case you agree with my hunch.

Augustine Aykara · Accepted Answer · 2020-01-07 17:15:42Z

0

If you are using VSCode then try this method :
Delete .vscode folder in your project directory and rerun the program.

answered Jan 7, 2020 at 17:15

Augustine Aykara

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Comments

Ali_R · Accepted Answer · 2021-03-11 11:42:48Z

0

In case someone is struggling with this what worked for me is to recreate ios folder. And -t works regardless of the location of the target or name of the target and without any need to have main.dart in your lib folder.

To recreate ios folder

rename ios folder to something like ios_old
run => flutter create fakeApp
open fakeApp, copy the ios folder to your project
migrate changes from ios_old (if you had any changes)
delete ios_old

answered Mar 11, 2021 at 11:42

Ali_R

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Comments

wickramage don malinda pathma · Accepted Answer · 2022-11-17 13:42:38Z

0

I think you already change the path of main.dart.If so You can drag and drop the main.dart file to lib folder.(lib/main.dart)

answered Nov 17, 2022 at 13:42

wickramage don malinda pathma

11 bronze badge

Comments

Adam · Accepted Answer · 2024-03-23 01:40:50Z

0

you probably just changed location of main.dart try running : flutter run yourPath/main.dart or whatever you named it

answered Mar 23, 2024 at 1:40

Adam

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Comments

zinxer · Accepted Answer · 2024-08-30 09:28:31Z

lib/Screen/SplashScreen/Splash.dart:10:8: Error: Error when reading 'lib/widgets/applogo.dart': No such file or directory import 'package:eshop_multivendor/widgets/applogo.dart'; ^ lib/Screen/Auth/Login.dart:12:8: Error: Error when reading 'lib/widgets/applogo.dart': No such file or directory import 'package:eshop_multivendor/widgets/applogo.dart'; ^ lib/Screen/Auth/SignInUpAcc.dart:3:8: Error: Error when reading 'lib/widgets/applogo.dart': No such file or directory import 'package:eshop_multivendor/widgets/applogo.dart'; ^ lib/Screen/Auth/SendOtp.dart:5:8: Error: Error when reading 'lib/widgets/applogo.dart': No such file or directory import 'package:eshop_multivendor/widgets/applogo.dart'; ^ lib/Screen/Auth/Verify_Otp.dart:8:8: Error: Error when reading 'lib/widgets/applogo.dart': No such file or directory import 'package:eshop_multivendor/widgets/applogo.dart'; ^ lib/Screen/Auth/Set_Password.dart:2:8: Error: Error when reading 'lib/widgets/applogo.dart': No such file or directory import 'package:eshop_multivendor/widgets/applogo.dart'; ^ lib/Screen/Auth/SignUp.dart:8:8: Error: Error when reading 'lib/widgets/applogo.dart': No such file or directory import 'package:eshop_multivendor/widgets/applogo.dart'; ^ lib/Screen/Auth/Login.dart:1099:20: Error: Couldn't find constructor 'AppLogo'. child: const AppLogo(), ^^^^^^^ lib/Screen/Auth/SignInUpAcc.dart:30:20: Error: Couldn't find constructor 'AppLogo'. child: const AppLogo(), ^^^^^^^ lib/Screen/Auth/SendOtp.dart:696:20: Error: Couldn't find constructor 'AppLogo'. child: const AppLogo(), ^^^^^^^ lib/Screen/Auth/Verify_Otp.dart:285:20: Error: Couldn't find constructor 'AppLogo'. child: const AppLogo(), ^^^^^^^ lib/Screen/Auth/Set_Password.dart:393:20: Error: Couldn't find constructor 'AppLogo'. child: const AppLogo(), ^^^^^^^ lib/Screen/Auth/SignUp.dart:562:20: Error: Couldn't find constructor 'AppLogo'. child: const AppLogo(), ^^^^^^^ Target kernel_snapshot failed: Exception

FAILURE: Build failed with an exception.

What went wrong: Execution failed for task ':app:compileFlutterBuildDebug'.

Process 'command '/home/user/snap/flutter/common/flutter/bin/flutter'' finished with non-zero exit value 1

Try:

Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

Get more help at https://help.gradle.org

BUILD FAILED in 16s Running Gradle task 'assembleDebug'... 16.6s Error: Gradle task assembleDebug failed with exit code 1

It looks like this problem is missing files/directory imports. Why didn't you suggest they resolve that first?
hello, this is answer section. If you have a question for your problem please add new question and explain your problem there thanks.

UCHE CHINEDU · Accepted Answer · 2024-11-05 22:21:14Z

0

In my own case, it was a trailing space in the lib folder. like this lib /main instead of lib/main You should probably double check if you encounter this issue.

answered Nov 5, 2024 at 22:21

UCHE CHINEDU

1

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