No static method metafactory

Try to switch to Java 8 compatibility mode, for proper de-sugaring of some library:

android {

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

    kotlinOptions {
        jvmTarget = "1.8"
    }
}

Besides, Google JSON API might rather need the GsonConverterFactory.

In my case, it was not for retrofit. I was using a local library module (named Android XML to PDF generator) that was using Java version 1.8 (for using Rx Java), but my app level Java version was less than 1.8.

So I simply added in the following lines in my app level build.gradle -

compileOptions {
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8
}

Then it worked for me!

You can resolve this error by setting compileOptions in build.gradle(app) file.

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

Try to refactor the Retrofit dependencies.

Write this:

implementation 'com.squareup.retrofit2:retrofit:2.4.0'
implementation 'com.squareup.retrofit2:converter-gson:2.2.0'