Uploading Android App Bundle to Google Play Console - The Android App Bundle was not signed

Whilst uploading a new version of our Android app, I had the following error display

The Android App Bundle was not signed.

The short answer is in the build type release debuggable isn't set to false.

How to solve

In the build.gradle file (path: android > app)

{
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
        debug {
            debuggable false
            jniDebuggable false
            renderscriptDebuggable false
            minifyEnabled false
        }
    }
}

Debuggable hadn't been set to false for release... it was missing all together.  The updated file looks like:

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
            debuggable false
            jniDebuggable false
            renderscriptDebuggable false
        }
        debug {
            debuggable false
            jniDebuggable false
            renderscriptDebuggable false
            minifyEnabled false
        }
    }

This can also be edited through Android Studio... File > Project Structure.  Then go to Build Variants and select release.