diff --git a/htdocs/install/upgrade.php b/htdocs/install/upgrade.php
index 14c392eeedf..fe47dde0b99 100644
--- a/htdocs/install/upgrade.php
+++ b/htdocs/install/upgrade.php
@@ -25,11 +25,14 @@
  */
 
 include_once("./inc.php");
-if (file_exists($conffile)) include_once($conffile);
+if (! file_exists($conffile))
+{
+	print 'Error: Dolibarr config file was not found. This may means that Dolibarr is not installed yet. Please call the page "/install/install.php" instead of "/install/upgrade.php").';
+}
+require_once($conffile);
 require_once($dolibarr_main_document_root."/lib/databases/".$dolibarr_main_db_type.".lib.php");
 require_once($dolibarr_main_document_root."/lib/admin.lib.php");
 
-
 $grant_query='';
 $etape = 2;
 $ok = 0;
diff --git a/htdocs/install/upgrade2.php b/htdocs/install/upgrade2.php
index 7318b40413d..7a3730cabe3 100644
--- a/htdocs/install/upgrade2.php
+++ b/htdocs/install/upgrade2.php
@@ -25,7 +25,11 @@
  */
 
 include_once('./inc.php');
-if (file_exists($conffile)) include_once($conffile);
+if (! file_exists($conffile))
+{
+	print 'Error: Dolibarr config file was not found. This may means that Dolibarr is not installed yet. Please call the page "/install/install.php" instead of "/install/upgrade.php").';
+}
+require_once($conffile);
 require_once($dolibarr_main_document_root . "/lib/databases/".$dolibarr_main_db_type.".lib.php");
 require_once($dolibarr_main_document_root . '/facture.class.php');
 require_once($dolibarr_main_document_root . '/propal.class.php');