Flutter: Gradle build failed to produce an .apk file. It's likely that this file was generated under <app_root>\build, but the tool couldn't find it

in my case I have a multi flavor app like this:

update 04/15/2021:

{
    // Use IntelliSense to learn about possible attributes.
    // Hover to view descriptions of existing attributes.
    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
    "version": "0.2.0",
    "configurations": [
            {
                    "name": "YOUR_PROJECT_NAME",
                    "program": "lib/main.dart",
                    "request": "launch",
                    "type": "dart",
                    "args": [
                            "--flavor",
                            "ADD_YOUR_FLAVOR_NAME_HERE" //development or staging or production
                        ]
            }
    ]

Another way:

 android {

    ...

    buildTypes {
        release {
            // TODO: Add your own signing config for the release build.
            // Signing with the debug keys for now, so `flutter run --release` works.
            signingConfig signingConfigs.debug
        }
    }

    flavorDimensions "flavor-type"

    productFlavors{
        development{
            dimension "flavor-type"
        }
        staging{
            dimension "flavor-type"
        }
        production{
            dimension "flavor-type"
        }
    }
}

So if you want to run app you have to write the flavor name and then the class name that hold main() function

flutter run --flavor staging -t lib/main_staging.dart

and I solved my error and built the .apk

Added the flavor name in Build name from Edit Configurations and it worked!

Ok, I found that it's args in launch.json if you use vscode