Laravel 2FA error

why is it returns like this where i click complete registration? i checked the route and the code but it seems it didn't go through the controller. can anyone help me im stuck

public function register(Request $request)
{

    if(DB::table('users')->where('student_no', '=', $request['student_no'])->exists()){
        $user = User::where('student_no', '=', $request['student_no'])->first();

        return back()->withErrors(['message' => 'student number is already taken ']);

    }else {

        //Validate the incoming request using the already included validator method
        $this->validator($request->all())->validate();

        // Initialise the 2FA class
        $google2fa = app('pragmarx.google2fa');

        // Save the registration data in an array
        $registration_data = $request->all();

        // Add the secret key to the registration data
        $registration_data["google2fa_secret"] = $google2fa->generateSecretKey();

        // Save the registration data to the user session for just the next request
        $request->session()->flash('registration_data', $registration_data);

        // Generate the QR image. This is the image the user will scan with their app
        // to set up two factor authentication
        $QR_Image = $google2fa->getQRCodeInline(
            config('app.name'),
                        $registration_data['email'],
                        $registration_data['google2fa_secret']
        );

        // Pass the QR barcode image to our view
        return view('google2fa.register', ['QR_Image' => $QR_Image, 'secret' => $registration_data['google2fa_secret']]);



    }
}

public function completeRegistration(Request $request)
{

    // add the session data back to the request input
    $request->merge(session('registration_data'));

    // Call the default laravel authentication
    return $this->registration($request);
}

Route

        Route::get('register', 'RegisterController@showRegistrationForm')->name('register');
        Route::post('register', 'RegisterController@register')->name('register.post');
        Route::get('/complete-registration', 'RegisterController@completeRegistration')->name('complete-registration');