[PrestaShopException] vat number

[simonetb]

During order (in address tab) users that use old browser view error 500 on monitor.

I use prestashop 1.7.1.0. How can i solve?
Thank you!

La proprietà Address->vat_number è vuota.
at line 944 in file classes/ObjectModel.php

}
$message = $this->validateField($field, $this->$field);
if ($message !== true) {
if ($die) {
throw new PrestaShopException($message);
}
return $error_return ? $message : false;
}
}
ObjectModelCore->validateFields - [line 272 - classes/ObjectModel.php]
ObjectModelCore->getFields - [line 518 - classes/ObjectModel.php]
ObjectModelCore->add - [line 174 - classes/Address.php] - [2 Arguments]
AddressCore->add - [line 476 - classes/ObjectModel.php] - [2 Arguments]
ObjectModelCore->save - [line 76 - classes/form/CustomerAddressPersister.php]
CustomerAddressPersisterCore->save - [line 145 - classes/form/CustomerAddressForm.php] - [2 Arguments]
CustomerAddressFormCore->submit - [line 111 - classes/checkout/CheckoutAddressesStep.php]
CheckoutAddressesStepCore->handleRequest - [line 57 - classes/checkout/CheckoutProcess.php] - [1 Arguments]
CheckoutProcessCore->handleRequest - [line 202 - controllers/front/OrderController.php] - [1 Arguments]
OrderControllerCore->initContent - [line 205 - classes/controller/Controller.php]
ControllerCore->run - [line 369 - classes/Dispatcher.php]
DispatcherCore->dispatch - [line 28 - index.php]