Index: trunk/core/install/upgrades.php
===================================================================
diff -u -N -r7855 -r8038
--- trunk/core/install/upgrades.php	(.../upgrades.php)	(revision 7855)
+++ trunk/core/install/upgrades.php	(.../upgrades.php)	(revision 8038)
@@ -6,16 +6,69 @@
 	 *
 	 */
 	class CoreUpgrades extends kHelper {
-	
+		
 		/**
 		 * Changes table structure, where multilingual fields of TEXT type are present
 		 *
 		 * @param string $mode when called mode {before, after)
 		 */
 		function Upgrade_4_0_2($mode)
 		{
+			$ml_helper =& $this->Application->recallObject('kMultiLanguageHelper');
+			/* @var $ml_helper kMultiLanguageHelper */
 			
+			$lang_count = $ml_helper->getLanguageCount();
+			$this->Application->UnitConfigReader->iterateConfigs( Array (&$this, 'updateTextFields', $lang_count) );
 		}
+
+		/**
+		 * Callback function, that makes all ml fields of text type null with same default value
+		 *
+		 * @param string $prefix
+		 * @param Array $config_data
+		 * @param int $language_count
+		 * @return bool
+		 */
+		function updateTextFields($prefix, &$config_data, $language_count)
+		{
+			if (!isset($config_data['TableName']) || !isset($config_data['Fields'])) {
+				// invalid config found or prefix not found
+				return false;
+			}
+			
+			$table_name = $config_data['TableName'];
+			$table_structure = $this->Conn->Query('DESCRIBE '.$table_name, 'Field');
+			if (!$table_structure) {
+				// table not found
+				return false;
+			}
+			
+			$sqls = Array ();
+			foreach ($config_data['Fields'] as $field => $options) {
+				if (isset($options['formatter']) && $options['formatter'] == 'kMultiLanguage' && !isset($options['master_field'])) {
+					// update all l<lang_id>_<field_name> fields (new format)
+					for ($i = 1; $i <= $language_count; $i++) {
+						$ml_field = 'l'.$i.'_'.$field;
+						if ($table_structure[$ml_field]['Type'] == 'text') {
+							$sqls[] = 'CHANGE '.$ml_field.' '.$ml_field.' TEXT NULL DEFAULT NULL';
+						}
+					}
+					
+					// update <field_name> if found (old format)
+					if (isset($table_structure[$field]) && $table_structure[$field]['Type'] == 'text') {
+						$sqls[] = 'CHANGE '.$field.' '.$field.' TEXT NULL DEFAULT NULL';
+					}
+				}
+			}
+			
+			if ($sqls) {
+				$sql = 'ALTER TABLE '.$table_name.' '.implode(', ', $sqls);
+				$this->Conn->Query($sql);
+			}
+			
+			return true;
+		}
+			
 	}
 	
 ?>
\ No newline at end of file