public function on404() {

    // 404 Fallback message.
    $response = '
    <div class="box">
      <div class="row">
        <div class="col-xs-3 col-sm-2 col-md-2 text-center mrgn-tp-md">
          <span class="glyphicon glyphicon-warning-sign glyphicon-error"></span>
        </div>
        <div class="col-xs-9 col-sm-10 col-md-10">
          <h2 class="mrgn-tp-md">' . $this->t('We couldn\'t find that Web page') . '</h2>
          <p class="pagetag"><strong>' . $this->t('Error 404') . '</strong></p>
        </div>
      </div>
      <p class="mrgn-tp-md">' . $this->t('We\'re sorry you ended up here. Sometimes a page gets moved or deleted.') . '</p>
    </div>';

    // Lookup our custom 404 content block.
    $block_id = $this->blockContentStorage->loadByProperties([
      'info' => '404',
      'type' => 'basic',
    ]);
    if (!empty($block_id)) {
      $response = $this->blockViewBuilder->view(reset($block_id));
    }

    return [
      '#type' => 'container',
      '#markup' => render($response),
      '#attributes' => [
        'class' => '404 error',
      ],
      '#weight' => 0,
    ];
  }
public function on404() {

    // 404 Fallback message.
    $response = '
    <div class="box">
      <div class="row">
        <div class="col-xs-3 col-sm-2 col-md-2 text-center mrgn-tp-md">
          <span class="glyphicon glyphicon-warning-sign glyphicon-error"></span>
        </div>
        <div class="col-xs-9 col-sm-10 col-md-10">
          <h2 class="mrgn-tp-md">' . $this->t('We couldn\'t find that Web page') . '</h2>
          <p class="pagetag"><strong>' . $this->t('Error 404') . '</strong></p>
        </div>
      </div>
      <p class="mrgn-tp-md">' . $this->t('We\'re sorry you ended up here. Sometimes a page gets moved or deleted.') . '</p>
    </div>';

    // Lookup our custom 404 content block.
    $block_id = $this->blockContentStorage->loadByProperties([
      'info' => '404',
      'type' => 'basic',
    ]);
    if (!empty($block_id)) {
      $response = $this->blockViewBuilder->view(reset($block_id));
    }

    return [
      '#type' => 'container',
      '#markup' => render($response),
      '#attributes' => [
        'class' => '404 error',
      ],
      '#weight' => 0,
    ];
  }
public function on404 ( ) { // 404 Fallback message. $ response = '
    <div class="box">
      <div class="row">
        <div class="col-xs-3 col-sm-2 col-md-2 text-center mrgn-tp-md">
          <span class="glyphicon glyphicon-warning-sign glyphicon-error"></span>
        </div>
        <div class="col-xs-9 col-sm-10 col-md-10">
          <h2 class="mrgn-tp-md">' . $ this -> t ( 'We couldn\'t find that Web page' ) . '</h2>
          <p class="pagetag"><strong>' . $ this -> t ( 'Error 404' ) . '</strong></p>
        </div>
      </div>
      <p class="mrgn-tp-md">' . $ this -> t ( 'We\'re sorry you ended up here. Sometimes a page gets moved or deleted.' ) . '</p>
    </div>' ; // Lookup our custom 404 content block. $ block_id = $ this -> blockContentStorage -> loadByProperties ( [ 'info' => '404' , 'type' => 'basic' , ] ) ; if ( ! empty ( $ block_id ) ) { $ response = $ this -> blockViewBuilder -> view ( reset ( $ block_id ) ) ; } return [ '#type' => 'container' , '#markup' => render ( $ response ) , '#attributes' => [ 'class' => '404 error' , ] , '#weight' => 0 , ] ; }
The default 404 content.

@return array
A render array containing the message to display for 404 pages.
The default 404 content .