Why is the registration on the site not going through?

Question

Yii

Hello, after registration, it redirects to a page with the "Page not found" error, I don’t understand why this happened ... Registration is enabled on all pages, that is, all controllers have the same code .. I can’t register on more than one page ...
SignupController.php

<?php

class SignupController extends Controller
{
    public function actions()
    {
        return array(
            'captcha'=>array(
                'class' => 'CaptchaAction',
            )
        );
    }

    public function actionIndex()
    {
        $form = new User(User::SCENARIO_SIGNUP);

        if (isset($_POST['User']) && $_POST['action'] == User::SCENARIO_SIGNUP)
        {
            $form->attributes = $_POST['User'];

            if ($form->validate())
            {
                $transaction = Yii::app()->db->beginTransaction();
                try
                {
                    $form->create();
                    $transaction->commit();

                    // send register info
                    $user = User::model()->findByAttributes(array('email' => $form->email));
                    $user->sendRegisterInfo();

                    Yii::app()->user->setFlash('success', 'Вы успешно зарегистрировались. На указанный E-mail было отправлено письмо с паролем для входа.');
                }
                catch (Exception $e)
                {
                    $transaction->rollback();
                    Yii::app()->user->setFlash('error', Yii::t('main', 'unknown_error'));
                }
            }
        }

        $this->render('index', array(
            'form'=>$form
        ));
    }
}

signup.php

<?php echo CHtml::beginForm(); ?>
                        <div class="row">
                            <div class="col-12">
                                <div class="form-group" style="color: red;">
                                    <p><?php $this->widget('FlashMessagesWidget'); ?>
                                        <?php echo DHtml::errorSummary($form, '', array('style'=>'color: red;')); ?></p>
                                </div>
                            </div>
                            <div class="col-lg-6">
                                <div class="form-group">
                                    <?php echo CHtml::activeTextField($form, 'username', array('class'=>'form-control mb-30', 'placeholder'=>'Введите логин')); ?>
                                </div>
                            </div>
                            <div class="col-lg-6">
                                <div class="form-group">
                                    <?php echo CHtml::activeTextField($form, 'email', array('class'=>'form-control mb-30', 'placeholder'=>'Введите email')); ?>
                                </div>
                            </div>
                            <div class="contact-heading mb-50" style="color: red; text-align: center; margin: 0 auto; width: 100%;">
                                <p>
                                    <?php if ($form->hasRefererCookie()) { ?>
                                    <?php $refererUsername = $form->refererUsernameFromCookie(); ?>
                                    <?php echo CHtml::activeHiddenField($form, 'inviterUsername', array('value' => $refererUsername)); ?>
                                </p>
                            </div>
                            <div class="col-12">
                                <div class="form-group">
                                    <input type="text" class="form-control mb-30" value="Вас пригласил: <?php echo $refererUsername; ?>" readonly style="width: 100%;">
                                </div>
                            </div>
                            <?php } ?>
                            <div class="col-12">
                                <div class="form-group form-control mb-30" style="text-align: center; height: 62px; cursor: pointer;">
                                    <img <?php $this->widget('CCaptcha'); ?>
                                </div>
                            </div>
                            <div class="col-12">
                                <div class="form-group">
                                    <?php echo CHtml::activeTextField($form, 'verifyCode', array('placeholder'=>$form->getAttributeLabel('enterVerifyCode'), 'class'=>'form-control mb-30')); ?>
                                </div>
                            </div>
                            <div class="col-12">
                                <?php echo CHtml::hiddenField('action', User::SCENARIO_SIGNUP); ?>
                                <button class="btn uza-btn btn-3 mt-15" style="width: 100%;">Зарегистрироваться</button>
                            </div>
                        </div>
                    <?php echo CHtml::endForm(); ?>