MC-42215: Some item cannot be saved - Make sure the To Date is later than or the same as the From Date

- fix

Author: o-dubovyk

app/code/Magento/Catalog/Model/Attribute/Backend/Startdate.php

@@ -7,7 +7,7 @@
 
 /**
  *
- * Speical Start Date attribute backend
+ * Special Start Date attribute backend
  *
  * @api
  *
@@ -83,7 +83,7 @@ public function validate($object)
         $attr = $this->getAttribute();
         $maxDate = $attr->getMaxValue();
         $startDate = $this->_getValueForSave($object);
-        if ($startDate === false) {
+        if ($startDate === false || $startDate === null) {
             return true;
         }