Error al cambiar estado del pedido

[anxanet]

He actualizado la version de prestashop 1.5 a 1.5.6 y la tenia en local, ayer la subi al servidor y ahora cuando quiero cambiar el estado del pedido, por ejemplo de En proceso a Enviado (o cualquier otro) me salta el siguiente error, que no tengo ni idea de que puede ser:

 

 

[PrestaShopException]

Property Order->date_add is not valid
at line 837 in file classes/ObjectModel.php

831.

832.                   $message = $this->validateField($field, $this->$field);

833.                   if ($message !== true)

834.                   {

835.                           if ($die)

836.                                  throw new PrestaShopException($message);

837.                           return $error_return ? $message : false;

838.                   }

839.           }

840.

841.           return true;

• ObjectModelCore->validateFields - [line 255 - classes/ObjectModel.php] - [0 Argument]
• ObjectModelCore->getFields - [line 277 - classes/order/Order.php] - [0 Argument]
• OrderCore->getFields - [line 596 - classes/ObjectModel.php] - [0 Argument]
• ObjectModelCore->update - [line 286 - classes/order/OrderHistory.php] - [0 Argument]
• OrderHistoryCore->changeIdOrderState - [line 349 - controllers/admin/AdminOrdersController.php] - [3 Arguments]
• 343.                                           $history->id_employee = (int)$this->context->employee->id;
• 344.
• 345.                                           $use_existings_payment = false;
• 346.                                           if (!$order->hasInvoice())
• 347.                                                   $use_existings_payment = true;
• 348.                                           $history->changeIdOrderState((int)$order_state->id, $order, $use_existings_payment);
• 349.
• 350.                                           $carrier = new Carrier($order->id_carrier, $order->id_lang);
• 351.                                           $templateVars = array();
• 352.                                           if ($history->id_order_state == Configuration::get('PS_OS_SHIPPING') && $order->shipping_number)
• 353.                                                   $templateVars = array('{followup}' => str_replace('@', $order->shipping_number, $carrier->url));
• AdminOrdersControllerCore->postProcess - [line 158 - classes/controller/Controller.php] - [0 Argument]
• ControllerCore->run - [line 348 - classes/Dispatcher.php] - [0 Argument]
• DispatcherCore->dispatch - [line 53 - admin2775/index.php] - [0 Argument]

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