diff --git a/administrator/components/com_admin/sql/updates/mysql/4.0.0-2019-04-22.sql b/administrator/components/com_admin/sql/updates/mysql/4.0.0-2019-04-22.sql
new file mode 100644
index 0000000000000..9459c3d8abaaa
--- /dev/null
+++ b/administrator/components/com_admin/sql/updates/mysql/4.0.0-2019-04-22.sql
@@ -0,0 +1,8 @@
+ALTER TABLE `#__contact_details` MODIFY `publish_up` datetime NULL DEFAULT NULL;
+ALTER TABLE `#__contact_details` MODIFY `publish_down` datetime NULL DEFAULT NULL;
+ALTER TABLE `#__contact_details` MODIFY `checked_out_time` datetime NULL DEFAULT NULL;
+
+UPDATE `#__contact_details` SET
+	`publish_up` = CASE WHEN `publish_up` IN ('0000-00-00 00:00:00', '1000-01-01 00:00:00') THEN NULL ELSE `publish_up` END,
+	`publish_down` = CASE WHEN `publish_down` IN ('0000-00-00 00:00:00', '1000-01-01 00:00:00') THEN NULL ELSE `publish_down` END,
+	`checked_out_time` = CASE WHEN `checked_out_time` IN ('0000-00-00 00:00:00', '1000-01-01 00:00:00') THEN NULL ELSE `checked_out_time` END;
diff --git a/administrator/components/com_admin/sql/updates/postgresql/4.0.0-2019-04-22.sql b/administrator/components/com_admin/sql/updates/postgresql/4.0.0-2019-04-22.sql
new file mode 100644
index 0000000000000..32d91acc14636
--- /dev/null
+++ b/administrator/components/com_admin/sql/updates/postgresql/4.0.0-2019-04-22.sql
@@ -0,0 +1,13 @@
+ALTER TABLE "#__contact_details" ALTER COLUMN "publish_up" DROP NOT NULL;
+ALTER TABLE "#__contact_details" ALTER COLUMN "publish_up" DROP DEFAULT;
+
+ALTER TABLE "#__contact_details" ALTER COLUMN "publish_down" DROP NOT NULL;
+ALTER TABLE "#__contact_details" ALTER COLUMN "publish_down" DROP DEFAULT;
+
+ALTER TABLE "#__contact_details" ALTER COLUMN "checked_out_time" DROP NOT NULL;
+ALTER TABLE "#__contact_details" ALTER COLUMN "checked_out_time" DROP DEFAULT;
+
+UPDATE "#__contact_details" SET
+	"publish_up" = CASE WHEN "publish_up" = '1970-01-01 00:00:00' THEN NULL ELSE "publish_up" END,
+	"publish_down" = CASE WHEN "publish_down" = '1970-01-01 00:00:00' THEN NULL ELSE "publish_down" END,
+	"checked_out_time" = CASE WHEN "checked_out_time" = '1970-01-01 00:00:00' THEN NULL ELSE "checked_out_time" END;
diff --git a/administrator/components/com_contact/Table/ContactTable.php b/administrator/components/com_contact/Table/ContactTable.php
index 64d7dee246efa..04f53ce83dc45 100644
--- a/administrator/components/com_contact/Table/ContactTable.php
+++ b/administrator/components/com_contact/Table/ContactTable.php
@@ -27,6 +27,14 @@
  */
 class ContactTable extends Table
 {
+	/**
+	 * Indicates that columns fully support the NULL value in the database
+	 *
+	 * @var    boolean
+	 * @since  __DEPLOY_VERSION__
+	 */
+	protected $_supportNullValue = true;
+
 	/**
 	 * Ensure the params and metadata in json encoded in the bind method
 	 *
@@ -58,7 +66,7 @@ public function __construct(DatabaseDriver $db)
 	 *
 	 * @since   1.6
 	 */
-	public function store($updateNulls = false)
+	public function store($updateNulls = true)
 	{
 		// Transform the params field
 		if (is_array($this->params))
@@ -91,18 +99,6 @@ public function store($updateNulls = false)
 			}
 		}
 
-		// Set publish_up to null date if not set
-		if (!$this->publish_up)
-		{
-			$this->publish_up = $this->_db->getNullDate();
-		}
-
-		// Set publish_down to null date if not set
-		if (!$this->publish_down)
-		{
-			$this->publish_down = $this->_db->getNullDate();
-		}
-
 		// Set xreference to empty string if not set
 		if (!$this->xreference)
 		{
@@ -253,9 +249,20 @@ public function check()
 			$this->metadata = '{}';
 		}
 
-		if (empty($this->modified))
+		// Set publish_up, publish_down to null if not set
+		if (!$this->publish_up)
+		{
+			$this->publish_up = null;
+		}
+
+		if (!$this->publish_down)
+		{
+			$this->publish_down = null;
+		}
+
+		if (!$this->modified)
 		{
-			$this->modified = $this->getDbo()->getNullDate();
+			$this->modified = $this->created;
 		}
 
 		return true;
diff --git a/components/com_contact/Model/CategoryModel.php b/components/com_contact/Model/CategoryModel.php
index bbfb193c941bd..02e32764fdb83 100644
--- a/components/com_contact/Model/CategoryModel.php
+++ b/components/com_contact/Model/CategoryModel.php
@@ -180,8 +180,8 @@ protected function getListQuery()
 
 		if ($this->getState('filter.publish_date'))
 		{
-			$query->where('(a.publish_up = ' . $nullDate . ' OR a.publish_up <= ' . $nowDate . ')')
-				->where('(a.publish_down = ' . $nullDate . ' OR a.publish_down >= ' . $nowDate . ')');
+			$query->where('(' . $query->isNullDatetime('a.publish_up') . ' OR a.publish_up <= ' . $db->quote($nowDate) . ')')
+				->where('(' . $query->isNullDatetime('a.publish_down') . ' OR a.publish_down >= ' . $db->quote($nowDate) . ')');
 		}
 
 		// Filter by search in title
diff --git a/components/com_contact/Model/ContactModel.php b/components/com_contact/Model/ContactModel.php
index 13d83d9a5f159..f8a8368ec961c 100644
--- a/components/com_contact/Model/ContactModel.php
+++ b/components/com_contact/Model/ContactModel.php
@@ -215,8 +215,8 @@ public function getItem($pk = null)
 				if (is_numeric($published))
 				{
 					$query->where('(a.published = ' . (int) $published . ' OR a.published =' . (int) $archived . ')')
-						->where('(a.publish_up = ' . $nullDate . ' OR a.publish_up <= ' . $nowDate . ')')
-						->where('(a.publish_down = ' . $nullDate . ' OR a.publish_down >= ' . $nowDate . ')');
+						->where('(' . $query->isNullDatetime('a.publish_up') . ' OR a.publish_up <= ' . $db->quote($nowDate) . ')')
+						->where('(' . $query->isNullDatetime('a.publish_down') . ' OR a.publish_down >= ' . $db->quote($nowDate) . ')');
 				}
 
 				$db->setQuery($query);
diff --git a/components/com_contact/Model/FeaturedModel.php b/components/com_contact/Model/FeaturedModel.php
index 1a2148f228edb..96c4129265070 100644
--- a/components/com_contact/Model/FeaturedModel.php
+++ b/components/com_contact/Model/FeaturedModel.php
@@ -118,8 +118,8 @@ protected function getListQuery()
 			$date = Factory::getDate();
 			$nowDate = $db->quote($date->toSql());
 
-			$query->where('(a.publish_up = ' . $nullDate . ' OR a.publish_up <= ' . $nowDate . ')')
-				->where('(a.publish_down = ' . $nullDate . ' OR a.publish_down >= ' . $nowDate . ')');
+			$query->where('(' . $query->isNullDatetime('a.publish_up') . ' OR a.publish_up <= ' . $db->quote($nowDate) . ')')
+				->where('(' . $query->isNullDatetime('a.publish_down') . ' OR a.publish_down >= ' . $db->quote($nowDate) . ')');
 		}
 
 		// Filter by language
diff --git a/installation/sql/mysql/joomla.sql b/installation/sql/mysql/joomla.sql
index 3972a2bc9691f..0d478573183cb 100644
--- a/installation/sql/mysql/joomla.sql
+++ b/installation/sql/mysql/joomla.sql
@@ -283,7 +283,7 @@ CREATE TABLE IF NOT EXISTS `#__contact_details` (
   `default_con` tinyint(1) unsigned NOT NULL DEFAULT 0,
   `published` tinyint(1) NOT NULL DEFAULT 0,
   `checked_out` int(10) unsigned NOT NULL DEFAULT 0,
-  `checked_out_time` datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
+  `checked_out_time` datetime,
   `ordering` int(11) NOT NULL DEFAULT 0,
   `params` text NOT NULL,
   `user_id` int(11) NOT NULL DEFAULT 0,
@@ -305,8 +305,8 @@ CREATE TABLE IF NOT EXISTS `#__contact_details` (
   `metadata` text NOT NULL,
   `featured` tinyint(3) unsigned NOT NULL DEFAULT 0 COMMENT 'Set if contact is featured.',
   `xreference` varchar(50) NOT NULL DEFAULT '' COMMENT 'A reference to enable linkages to external data sets.',
-  `publish_up` datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
-  `publish_down` datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
+  `publish_up` datetime,
+  `publish_down` datetime,
   `version` int(10) unsigned NOT NULL DEFAULT 1,
   `hits` int(10) unsigned NOT NULL DEFAULT 0,
   PRIMARY KEY (`id`),
diff --git a/installation/sql/postgresql/joomla.sql b/installation/sql/postgresql/joomla.sql
index 8c3f062647995..80246996cb80c 100644
--- a/installation/sql/postgresql/joomla.sql
+++ b/installation/sql/postgresql/joomla.sql
@@ -288,7 +288,7 @@ CREATE TABLE IF NOT EXISTS "#__contact_details" (
   "default_con" smallint NOT NULL DEFAULT 0,
   "published" smallint NOT NULL DEFAULT 0,
   "checked_out" bigint NOT NULL DEFAULT 0,
-  "checked_out_time" timestamp without time zone NOT NULL DEFAULT '1970-01-01 00:00:00',
+  "checked_out_time" timestamp without time zone,
   "ordering" bigint NOT NULL DEFAULT 0,
   "params" text NOT NULL,
   "user_id" bigint NOT NULL DEFAULT 0,
@@ -310,8 +310,8 @@ CREATE TABLE IF NOT EXISTS "#__contact_details" (
   "metadata" text NOT NULL,
   "featured" smallint NOT NULL DEFAULT 0,
   "xreference" varchar(50) NOT NULL DEFAULT '',
-  "publish_up" timestamp without time zone NOT NULL DEFAULT '1970-01-01 00:00:00',
-  "publish_down" timestamp without time zone NOT NULL DEFAULT '1970-01-01 00:00:00',
+  "publish_up" timestamp without time zone,
+  "publish_down" timestamp without time zone,
   "version" bigint NOT NULL DEFAULT 1,
   "hits" bigint NOT NULL DEFAULT 0,
   PRIMARY KEY ("id")