Android app crashes on addAccountExplicitly(account, password, null);

In my case it was happening that I had another app installed on the device with the same account name and type, but with different signing cert that the one I was trying to install.

So it was crashing the app.

Checking the android doc for the method addAccountExplicity, it says:

This method requires the caller to have a signature match with the authenticator that owns the specified account.

That was my problem

1) Reason for crash was because the following snippet was missing in AndroidManifest.xml.

<service android:name="com.example.accounts.GenericAccountService">
    <intent-filter>
         <action android:name="android.accounts.AccountAuthenticator" />
    </intent-filter>
    <meta-data android:name="android.accounts.AccountAuthenticator" android:resource="@xml/authenticator" />
</service>

2) It is absolutely possible, even though best practice example is still missing.

3) No idea. Yet...

You are using "com.example" as unique identifier for your app,please check if it's same in "authenticator.xml"