diff --git a/modules/erp/direktverkauf/api/otc-order.php b/modules/erp/direktverkauf/api/otc-order.php
index 2ab425f..ac53a6e 100644
--- a/modules/erp/direktverkauf/api/otc-order.php
+++ b/modules/erp/direktverkauf/api/otc-order.php
@@ -53,7 +53,11 @@ if ($totalPrice === null || $totalPrice <= 0) {
 
 $orderDateTime = DateTimeImmutable::createFromFormat('!Y-m-d', $orderDate);
 $orderDateErrors = DateTimeImmutable::getLastErrors();
-if ($orderDateTime === false || $orderDateErrors === false || $orderDateErrors['warning_count'] > 0 || $orderDateErrors['error_count'] > 0) {
+if ($orderDateTime === false) {
+    json_response(422, ['ok' => false, 'error' => 'Invalid order date']);
+}
+
+if (is_array($orderDateErrors) && (($orderDateErrors['warning_count'] ?? 0) > 0 || ($orderDateErrors['error_count'] ?? 0) > 0)) {
     json_response(422, ['ok' => false, 'error' => 'Invalid order date']);
 }