Google SignIn API Exception 10

Approaching to the final stage of the authentification, but something is going wrong in handleSignInResult method. It returns Exception code 10 (Developer error) in logs. Google provides comprehensive description:

The application is misconfigured. This error is not recoverable and will be treated as fatal. The developer is an idiot...

What should I do to handle this (get an account) and finally retrive values from account?
Thank you in advance for your help!!!

MainActivity:

package ru.podgorny.carcall;

import ...

public class MainActivity extends AppCompatActivity {

        SignInButton signInButton;
        public static final int RC_SIGN_IN = 07;
        public static final String TAG = "MainActivity";
        TextView tw1;
        TextView tw2;


        GoogleSignInOptions gso;
        GoogleSignInClient mGSC;


        @Override
        protected void onCreate (Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.d(TAG, "Activity Works");
        findViews();

            gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
                    .requestEmail()
                    //.requestProfile()
                    .build();

            mGSC = GoogleSignIn.getClient(this, gso); //smth with mGSC variable....

             View.OnClickListener onClickListener = new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    onClick2(v);
                }
            };
             signInButton.setOnClickListener(onClickListener);




    }

    private void findViews() {
            Log.d (TAG, "findViews started");
        signInButton = findViewById(R.id.idButtonGoogle);

        tw1 = findViewById(R.id.textView1);
        tw1 = findViewById(R.id.textView2);

        Log.d(TAG, "Views finded");


    }

    public void onClick2(View view) {
            Log.d(TAG, "onClick started");
        switch (view.getId()) {
            case R.id.idButtonGoogle:
                signIn();
                break;
        }
        Log.d(TAG, "OnClick Started");
    }

    public void signIn() {

        Intent signInIntent = mGSC.getSignInIntent();
        startActivityForResult(signInIntent, RC_SIGN_IN);
        Log.d(TAG, "startActivityForResult works");

    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        Log.d(TAG, "OnActivityResult started");
        // Result returned from launching the Intent from GoogleSignInClient.getSignInIntent(...);
        if (requestCode == RC_SIGN_IN) {
            // The Task returned from this call is always completed, no need to attach
            // a listener.
            Log.d(TAG, "TASK started");
            Task<GoogleSignInAccount> task = GoogleSignIn.getSignedInAccountFromIntent(data);
            handleSignInResult(task);
            Log.d(TAG, "OnActivityResult returned");
        }
    }

    private void handleSignInResult(Task<GoogleSignInAccount> completedTask) {
        try {
            GoogleSignInAccount account = completedTask.getResult(ApiException.class);//ERROR -- Code 10
            Log.d(TAG, "Account received");


            updateUI(account);
            Log.d(TAG, "updateUI Launched");
        } catch (ApiException e) {

            Log.w(TAG, "signInResult:failed code=" + e.getStatusCode());
            updateUI(null);
        }
    }

    private void updateUI(GoogleSignInAccount account) {
            if (account!=null) {
                tw1.setText("OK");
                tw2.setText("Name: " + account.getGivenName() + ", Family name: " + account.getFamilyName() + ", Email: " + account.getEmail() /*+ " image: " +
                        account.getPhotoUrl()*/);
            }else {
                tw1.setText("SMTH wrong");
            }

        }

}

This error might happen if you are not using same project at console.developers.google and console.firebase.google.com. If project is same at both console make sure you have add your SHA1 Key properly. Get SHA1 from Android studio.

1. Open Android Studio
2. Open your Project
3. Click on Gradle (From Right Side Panel, you will see Gradle Bar)
4. Click on Refresh (Click on Refresh from Gradle Bar, you will see List Gradle scripts of your Project)
5. Click on Your Project (Your Project Name form List (root))
6. Click on Tasks
7. Click on Android
8. Double Click on signingReport (You will get SHA1 and MD5 in Run Bar(Sometimes it will be in Gradle Console))
9. Select app module from module selection dropdown to run or debug your application 
 You also need to get google-services.json from firebase console and put into your project.