Solutions

Resolving Unsigned APK Issue in Android Build

Encountered an issue with unsigned APKs? Our investigation revealed missing signingConfig in build.gradle.kts. By setting signingConfig directly within each product flavor, you can ensure your APKs are properly signed. Read on to see the solution and fix your build issues.

Stephen Li

Stephen Li

— 1 min read
Resolving Unsigned APK Issue in Android Build

Recently, we encountered an issue where the generated APK had no signing information. When using the following command:

keytool --printcert --jarfile <apk_file_path>

The output indicated that the APK was not a signed JAR file:

Not a signed jar file

Investigation

Upon investigating the build.gradle.kts file in our project, I found the following settings for the signingConfig:

productFlavors {
    create("app1") {
        dimension = "app"
        applicationId = "com.example.app1"
        versionCode = 1
        versionName = "1.0"
        createSigningConfig(name, "app1.properties")
    }
    create("app2") {
        isDefault = true
        dimension = "app"
        applicationId = "com.example.app2"
        versionCode = 1
        versionName = "1.0"
        createSigningConfig(name, "app2.properties")
    }
}

Solution

To ensure the APK is signed, set the signingConfig directly within each product flavor. The updated configuration should look like this:

productFlavors {
    create("app1") {
        dimension = "app"
        applicationId = "com.example.app1"
        versionCode = 1
        versionName = "1.0"
        signingConfig = createSigningConfig(name, "app1.properties")
    }
    create("app2") {
        isDefault = true
        dimension = "app"
        applicationId = "com.example.app2"
        versionCode = 1
        versionName = "1.0"
        signingConfig = createSigningConfig(name, "app2.properties")
    }
}

By setting the signingConfig on the product flavor, it will be used when building the application, ensuring that the APK is properly signed.

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