Patch-Magento_Catalog-M2.1-fix-product-auto-startdates.patch

--- Model/Attribute/Backend/Startdate.php
+++ Model/Attribute/Backend/Startdate.php
@@ -44,12 +44,6 @@ protected function _getValueForSave($object)
     {
         $attributeName = $this->getAttribute()->getName();
         $startDate = $object->getData($attributeName);
-        if ($startDate === false) {
-            return false;
-        }
-        if ($startDate == '' && $object->getSpecialPrice()) {
-            $startDate = $this->_localeDate->date();
-        }
 
         return $startDate;
     }

--- etc/events.xml
+++ etc/events.xml
@@ -51,6 +51,9 @@
     <event name="magento_catalog_api_data_categorytreeinterface_load_after">
         <observer name="legacy_categorytree_load_after" instance="Magento\Framework\EntityManager\Observer\AfterEntityLoad" />
     </event>
+    <event name="catalog_product_save_before">
+        <observer name="set_special_price_start_date" instance="Magento\Catalog\Observer\SetSpecialPriceStartDate" />
+    </event>
     <event name="admin_system_config_changed_section_catalog">
         <observer name="catalog_update_price_attribute" instance="Magento\Catalog\Observer\SwitchPriceAttributeScopeOnConfigChange" />
     </event>

--- /dev/null
+++ Observer/SetSpecialPriceStartDate.php
@@ -0,0 +1,45 @@
+<?php
+/**
+ * Copyright © 2013-2017 Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+namespace Magento\Catalog\Observer;
+
+use Magento\Framework\Event\ObserverInterface;
+
+/**
+ *  Set value for Special Price start date
+ */
+class SetSpecialPriceStartDate implements ObserverInterface
+{
+    /**
+     * @var \Magento\Framework\Stdlib\DateTime\TimezoneInterface
+     */
+    private $localeDate;
+
+    /**
+     * @param \Magento\Framework\Stdlib\DateTime\TimezoneInterface $localeDate
+     * @codeCoverageIgnore
+     */
+    public function __construct(\Magento\Framework\Stdlib\DateTime\TimezoneInterface $localeDate)
+    {
+        $this->localeDate = $localeDate;
+    }
+
+    /**
+     * Set the current date to Special Price From attribute if it empty
+     *
+     * @param \Magento\Framework\Event\Observer $observer
+     * @return $this
+     */
+    public function execute(\Magento\Framework\Event\Observer $observer)
+    {
+        /** @var  $product \Magento\Catalog\Model\Product */
+        $product = $observer->getEvent()->getProduct();
+        if ($product->getSpecialPrice() && !$product->getSpecialFromDate()) {
+            $product->setData('special_from_date', $this->localeDate->date());
+        }
+
+        return $this;
+    }
+}