diff --git a/core/config.class.inc.php b/core/config.class.inc.php
index eeef51320..d15634b77 100644
--- a/core/config.class.inc.php
+++ b/core/config.class.inc.php
@@ -2270,7 +2270,7 @@ class Config
 		$oHandle = null;
 		$sConfig = null;
 
-		if (is_file($this->m_sFile))
+		if ($this->m_sFile!= null && is_file($this->m_sFile))
 		{
 			$oHandle = fopen($this->m_sFile, 'r');
 			$index = 0;
diff --git a/core/userrights.class.inc.php b/core/userrights.class.inc.php
index 071c2ffb1..8b44c6430 100644
--- a/core/userrights.class.inc.php
+++ b/core/userrights.class.inc.php
@@ -348,7 +348,7 @@ abstract class User extends cmdbAbstractObject
 		$aChanges = $this->ListChanges();
 		if (array_key_exists('login', $aChanges)) {
 			// Check login uniqueness
-			if (strcasecmp($this->Get('login'), $this->GetOriginal('login')) !== 0) {
+			if ( $this->GetOriginal('login')== null || strcasecmp($this->Get('login'), $this->GetOriginal('login')) !== 0) {
 				$sNewLogin = $aChanges['login'];
 				$oSearch = DBObjectSearch::FromOQL_AllData("SELECT User WHERE login = :newlogin");
 				if (!$this->IsNew()) {