When using supabase_flutter, why am I getting compileSdkVersion is not specified error?

Question

When I attempt to use Supabase flutter in an empty flutter project this happens:

• What went wrong: A problem occurred configuring project ':shared_preferences_android'.

Failed to notify project evaluation listener. Cannot invoke method substring() on null object compileSdkVersion is not specified. Please add it to build.gradle

This nightmare of a build error seemingly appeared around the time I upgraded to Flutter 3.19, but I'm not sure. Tried to fix to no avail.

app/build.gradle looks like so:

plugins {
    id "com.android.application"
    id "kotlin-android"
    id "dev.flutter.flutter-gradle-plugin"
}

def localProperties = new Properties()
def localPropertiesFile = rootProject.file('local.properties')
if (localPropertiesFile.exists()) {
    localPropertiesFile.withReader('UTF-8') { reader ->
        localProperties.load(reader)
    }
}

def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
if (flutterVersionCode == null) {
    flutterVersionCode = '1'
}

def flutterVersionName = localProperties.getProperty('flutter.versionName')
if (flutterVersionName == null) {
    flutterVersionName = '1.0'
}

android {
    namespace "com.example.exp"
    compileSdk flutter.compileSdkVersion
    ndkVersion flutter.ndkVersion

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

    kotlinOptions {
        jvmTarget = '1.8'
    }

    sourceSets {
        main.java.srcDirs += 'src/main/kotlin'
    }

    defaultConfig {
        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
        applicationId "com.example.app"
        // You can update the following values to match your application needs.
        // For more information, see: https://docs.flutter.dev/deployment/android#reviewing-the-gradle-build-configuration.
        minSdkVersion flutter.minSdkVersion
        targetSdkVersion flutter.targetSdkVersion
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
    }

    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
        }
    }
}

flutter {
    source '../..'
}

dependencies {}

Answer 1

Okay false alarm. Apparently had nothing to do with supabase. First I performed flutter pub cache repair which revealed a few other issues, first adding a missing line to my gradle defualt configs "manifestPlaceholders += [appAuthRedirectScheme: "com.example.ex"]", then later updating my kotlin version, eventually requiring me to add multidex support to my project. Strangely, it all works now. These issues set upon me quite quickly and I was confused how I got here. The more you know! Hope this helps someone else.