Won't add to cart. Undefined index: components

What version of Webform Rules module are you running? I was getting the same issue when using Webform Rules 7.x-1.7.

Downgrading Webform Rules module back to 7.x-1.6 fixed the issue for me.

Here is a patch I applied that seems to work with Webform Rules 7.x-1.7:

In commerce_webform_get_products_from_webform_submission() in commerce_webform.module modify this function from this:

function commerce_webform_get_products_from_webform_submission($submission) {
  $product_ids = array();
  $products = array();
  $data = array();

  $components = $submission['components'];

  foreach ($components as $component) {
    if ($component['component']['type'] == 'productfield') {
      foreach ($component['value'] as &$value) {
        $value = json_decode($value);
        if (!empty($value->product_id) && $value->quantity > 0) {
          $product_ids[] = $value->product_id;
          if (empty($data[$value->product_id])) {
            $data[$value->product_id] = $value;
            $data[$value->product_id]->required = $component['component']['required'];
            $data[$value->product_id]->choose_quantity = $component['component']['extra']['choose_quantity'];
          }
          else {
            // Now we need to change the quantity.
            $data[$value->product_id]->quantity = $data[$value->product_id]->quantity + $value->quantity;
          }
        }
      }
    }
  }

  $products = commerce_product_load_multiple($product_ids);

  foreach ($products as $product) {
    $data[$product->product_id]->product = $product;
  }

  return $data;
}

Change it to this:

function commerce_webform_get_products_from_webform_submission($submission) {
  $product_ids = array();
  $products = array();
  $data = array();

  $webform_node = reset($submission);
  $webform = node_load($webform_node->nid);
  $components = $webform->webform['components'];

  foreach ($webform_node->data as $cid => $val) {
    $c_key = $components[$cid]['form_key'];
    $webform_node->components[$c_key] = array(
      'nid' => $components[$cid]['nid'],
      'cid' => $cid,
      'pid' => $components[$cid]['pid'],
      'form_key' => $c_key,
      'name' => $components[$cid]['name'],
      'type' => $components[$cid]['type'],
      'value' => $val,
      'extra' => $components[$cid]['extra'],
      'required' => $components[$cid]['required'],
      'weight' => $components[$cid]['weight'],
      'page_num' => $components[$cid]['page_num'],
      );
  }

  foreach ($webform_node->components as $component) {
    if ($component['type'] == 'productfield') {
      foreach ($component['value'] as &$value) {
        $value = json_decode($value);
        if (!empty($value->product_id) && $value->quantity > 0) {
          $product_ids[] = $value->product_id;
          if (empty($data[$value->product_id])) {
            $data[$value->product_id] = $value;
            $data[$value->product_id]->required = $component['required'];
            $data[$value->product_id]->choose_quantity = $component['extra']['choose_quantity'];
          }
          else {
            // Now we need to change the quantity.
            $data[$value->product_id]->quantity = $data[$value->product_id]->quantity + $value->quantity;
          }
        }
      }
    }
  }

  $products = commerce_product_load_multiple($product_ids);

  foreach ($products as $product) {
    $data[$product->product_id]->product = $product;
  }

  return $data;
}