Flutter (Barcode_scan) build\barcode_scan\extracted-protos\main' specified for property '$4' does not exist

Question

I'm using this package to scan qr code. But I upgrade to 3.x version, have error:

[   +2 ms] FAILURE: Build failed with an exception.
[   +2 ms] * What went wrong:
[        ] Some problems were found with the configuration of task ':barcode_scan:generateDebugProto'.
[        ] > Directory '<projectName>\build\barcode_scan\extracted-protos\main' specified for property '$4' does not exist.
[  +19 ms] * Try:
[  +17 ms] 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.

I try add main folder to extracted-protos but when I run app, this folder is lost.

Answer 1

After spending 2 days trying to fix it. Finally I figured out how to:

Go to android folder > build.gradle file. After add line:

buildscript {
ext.kotlin_version = '1.3.61'
repositories {
    google()
    jcenter()
}

dependencies {
    classpath 'com.android.tools.build:gradle:3.5.0'
    classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    classpath 'com.google.protobuf:protobuf-gradle-plugin:0.8.12' //add this line
  }
}

And It work.