Firebase Android UI Email sign in bad request
<p>I implemented the new Firebase UI Auth sign in with this code:</p>

<pre><code> startActivityForResult(
            AuthUI.getInstance().createSignInIntentBuilder()
                    .setTheme(AuthUI.getDefaultTheme())
                    .setProviders(AuthUI.EMAIL_PROVIDER)
                    .setTosUrl(GOOGLE_TOS_URL)
                    .build(),
            RC_SIGN_IN);
</code></pre>

<p>last 2 days was working perfectly but now it crashes when entering an email and clicking the "Next" button.</p>

<p>This is the errror:</p>

<p><strong>com.google.android.gms.tasks.RuntimeExecutionException: com.google.firebase.FirebaseException: An internal error has occured. [ Backend Error ]</strong></p>

<p>Last point appears to be at </p>

<blockquote>
  <p>com.firebase.ui.auth.ui.AcquireEmailHelper$1.onComplete(AcquireEmailHelper.java:57)</p>
</blockquote>

<p>I have debugged that point, but there is just no error data.</p>

<p>Anyone have any idea why is this crashing? This happens when creating new users and trying to sign in with existing users too.</p>

<p>I am getting the instructions from :
<a href="https://github.com/firebase/FirebaseUI-Android" rel="nofollow">https://github.com/firebase/FirebaseUI-Android</a></p>