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, May 25 '18 at 06:02

score 101 · Accepted Answer · edited Dec 25 '22 at 21:01

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"
    }
  ]

Yep, it's working as expected. Thanks! flutter build apk lib/config/env_dev.dart — atereshkov, Feb 23 '19 at 21:49
If some one having issue file not found. Change to this "program": "./lib/staging_main.dart". — Rafsan Uddin Beg Rizan, Mar 02 '23 at 06:41

score 17 · Answer 2 · edited Nov 11 '20 at 12:24

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 '20 at 12:24

iDecode

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answered Jun 15 '18 at 07:56

Munish Thakur

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What if it's in another location? since i am using different files to build my prod and dev environment. – Rachit Rawat Sep 27 '18 at 11:56

score 9 · Answer 3 · answered Aug 26 '20 at 07:50

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

score 3 · Answer 4 · answered Dec 30 '18 at 23:28

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.

score 3 · Answer 5 · answered Jan 21 '19 at 03:53

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 '19 at 03:53

Steve Lukis

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score 3 · Answer 6 · edited Nov 17 '19 at 20:03

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 '19 at 20:03

m02ph3u5

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answered Nov 17 '19 at 19:44

Aminjoni Abdullozoda

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score 3 · Answer 7 · answered Jul 20 '21 at 01:09

3

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

answered Jul 20 '21 at 01:09

Mina Farid

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score 2 · Answer 8 · answered Apr 03 '19 at 18:26

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

score 2 · Answer 9 · answered Nov 11 '20 at 12:29

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"
            ]
        }]

score 1 · Answer 10 · edited Jul 01 '19 at 12:40

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 01 '19 at 12:40

adiga

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answered Jul 01 '19 at 12:32

Robinson Calderón

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score 1 · Answer 11 · answered Jun 08 '21 at 18:13

1

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

answered Jun 08 '21 at 18:13

Salah Qamachi

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Similar to https://stackoverflow.com/a/58618151/2227743 – Eric Aya Jun 08 '21 at 22:31

score 0 · Answer 12 · answered Apr 08 '19 at 06:44

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 08 '19 at 06:44

Sukhi

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Mehmet Bütün · Answer 13 · 2019-08-28T21:33:42.070

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 '19 at 21:33

answered Aug 28 '19 at 21:14

Mehmet Bütün

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daddy_ · Answer 14 · 2019-10-31T18:06:24.340

0

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

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

And doing this worked

edited Oct 31 '19 at 18:06

answered Oct 30 '19 at 03:00

daddy_

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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. – Yunnosch Oct 30 '19 at 03:26

score 0 · Answer 15 · answered Oct 30 '19 at 04:50

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.

score 0 · Answer 16 · answered Mar 11 '21 at 11:42

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

score 0 · Answer 17 · answered Nov 17 '22 at 13:42

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 '22 at 13:42

wickramage don malinda pathma

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score -1 · Answer 18 · answered Jan 07 '20 at 17:15

-1

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

answered Jan 07 '20 at 17:15

Augustine Aykara

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

18 Answers18

If you are using VSCODE

Linked