Index: install/upgrades.sql
===================================================================
--- install/upgrades.sql	(revision 13635)
+++ install/upgrades.sql	(working copy)
@@ -1892,3 +1892,6 @@
 DELETE FROM Permissions WHERE Permission LIKE 'in-portal:configuration_email%';
 DELETE FROM Permissions WHERE Permission LIKE 'in-portal:user_email%';
 DELETE FROM Phrase WHERE Phrase IN ('la_fld_FromToUser', 'la_col_FromToUser');
+
+# ===== v 5.1.0-B2 =====
+UPDATE Events SET Headers = NULL WHERE Headers = '';
\ No newline at end of file
Index: kernel/db/cat_dbitem.php
===================================================================
--- kernel/db/cat_dbitem.php	(revision 13557)
+++ kernel/db/cat_dbitem.php	(working copy)
@@ -107,10 +107,14 @@
 	function Update($id=null, $system_update=false)
 	{
 		$this->VirtualFields['ResourceId'] = Array();
-		$this->SetDBField('Modified', adodb_mktime() );
-		$this->UpdateFormattersSubFields(array('Modified'));
-		$this->SetDBField('ModifiedById', $this->Application->RecallVar('user_id'));
 
+		if ($this->GetChangedFields()) {
+			$now = adodb_mktime();
+			$this->SetDBField('Modified_date', $now);
+			$this->SetDBField('Modified_time', $now);
+			$this->SetDBField('ModifiedById', $this->Application->RecallVar('user_id'));
+		}
+
 		if ($this->useFilenames) {
 			$this->checkFilename();
 			$this->generateFilename();
Index: units/categories/categories_event_handler.php
===================================================================
--- units/categories/categories_event_handler.php	(revision 13581)
+++ units/categories/categories_event_handler.php	(working copy)
@@ -1304,7 +1304,9 @@
 			$object =& $event->getObject();
 			/* @var $object kDBItem */
 
-			$object->SetDBField('ModifiedById', $this->Application->RecallVar('user_id'));
+			if ($object->GetChangedFields()) {
+				$object->SetDBField('ModifiedById', $this->Application->RecallVar('user_id'));
+			}
 
 			$this->_beforeItemChange($event);
 		}
@@ -1556,8 +1558,10 @@
 
 			$now = adodb_mktime();
 
-			$object->SetDBField('Modified_date', $now);
-			$object->SetDBField('Modified_time', $now);
+			if ($object->GetChangedFields()) {
+				$object->SetDBField('Modified_date', $now);
+				$object->SetDBField('Modified_time', $now);
+			}
 
 			$object->setRequired('PageCacheKey', $object->GetDBField('OverridePageCacheKey'));
 			$object->SetDBField('Template', $this->_stripTemplateExtension( $object->GetDBField('Template') ));
Index: units/helpers/email_message_helper.php
===================================================================
--- units/helpers/email_message_helper.php	(revision 13557)
+++ units/helpers/email_message_helper.php	(working copy)
@@ -28,7 +28,7 @@
 				}
 			}
 
-			$ret['Headers'] = implode("\n", $headers);
+			$ret['Headers'] = $headers ? implode("\n", $headers) : null; // it's null field
 
 			$lines = array_slice($lines, $line_id + 1);
 
Index: units/modules/modules_event_handler.php
===================================================================
--- units/modules/modules_event_handler.php	(revision 13581)
+++ units/modules/modules_event_handler.php	(working copy)
@@ -84,13 +84,13 @@
 				}
 
 				$object->Load($id);
-
 				$object->SetDBField($status_field, $event->Name == 'OnMassApprove' ? 1 : 0);
+				$updated = $object->Update();
 
-				if ($object->Update()) {
+				if ($updated) {
 					$sql = 'UPDATE ' . TABLE_PREFIX . 'ImportScripts
-								SET Status = ' . ($event->Name == 'OnMassApprove' ? STATUS_ACTIVE : STATUS_DISABLED) . '
- 								WHERE Module = "' . $object->GetDBField('Name') . '"';
+							SET Status = ' . ($event->Name == 'OnMassApprove' ? STATUS_ACTIVE : STATUS_DISABLED) . '
+							WHERE Module = "' . $object->GetDBField('Name') . '"';
  					$this->Conn->Query($sql);
 
  					$event->status = erSUCCESS;