Error: Invoke-customs are only supported starting with Android O (--min-api 26)

What is relevant in this stacktrace is this line:

Caused by: com.android.tools.r8.utils.AbortException: Error: Invoke-customs are only supported starting with Android O (--min-api 26)

As there is not kotlin library in your dependencies, I assume you’re working with java. I would try answers in this issue

Try to add below to your app/build.gradle to make your Android project compilation be compatible with Java 8.

android {
    ....
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
    ....
}

for me following command in BUILD.GRADLE removed the error.

defaultConfig {
      applicationId "com.example.myapptestheader"
      minSdkVersion 21
      targetSdkVersion 29
      versionCode 1
      versionName "1.0"
      testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
   
      multiDexEnabled true
}

I just added

multiDexEnabled true

I had to remove useProguard true from the buildTypes configuration.

According to the documentation minifyEnabled true is enough to obfuscate your code with R8.

Example:

android {
    buildTypes {
        debug {
            versionNameSuffix "-dev"
            minifyEnabled true // <- remove this line when using instant run
            useProguard true // <- remove this line
            signingConfig signingConfigs.release
            proguardFiles getDefaultProguardFile('proguard-android.txt'), "proguard-rules.pro"
        }

        release {
            shrinkResources true
            minifyEnabled true
            useProguard true // <- remove this line
            signingConfig signingConfigs.release
            proguardFiles getDefaultProguardFile('proguard-android.txt'), "proguard-rules.pro"
        }
    }
}