diff --git a/htdocs/install/step5.php b/htdocs/install/step5.php
index 78d29584a30..81700c14824 100644
--- a/htdocs/install/step5.php
+++ b/htdocs/install/step5.php
@@ -219,12 +219,22 @@ if ($action == "set" || empty($action) || preg_match('/upgrade/i',$action))
 
             if ($success)
             {
+                // Insert MAIN_VERSION_FIRST_INSTALL in a dedicated transaction. So if it fails (when first install was already done), we can do other following requests.
                 $db->begin();
-
                 dolibarr_install_syslog('step5: set MAIN_VERSION_FIRST_INSTALL const to ' . $targetversion, LOG_DEBUG);
                 $resql=$db->query("INSERT INTO ".MAIN_DB_PREFIX."const(name,value,type,visible,note,entity) values(".$db->encrypt('MAIN_VERSION_FIRST_INSTALL',1).",".$db->encrypt($targetversion,1).",'chaine',0,'Dolibarr version when first install',0)");
-                //if (! $resql) dol_print_error($db,'Error in setup program');      // We ignore errors. Key may already exists
-                $conf->global->MAIN_VERSION_FIRST_INSTALL=$targetversion;
+                if ($resql)
+                {
+                    $conf->global->MAIN_VERSION_FIRST_INSTALL=$targetversion;
+                    $db->commit();
+                }
+                else
+                {
+                    //if (! $resql) dol_print_error($db,'Error in setup program');      // We ignore errors. Key may already exists
+                    $db->commit();
+                }
+
+                $db->begin();
 
                 dolibarr_install_syslog('step5: set MAIN_VERSION_LAST_INSTALL const to ' . $targetversion, LOG_DEBUG);
                 $resql=$db->query("DELETE FROM ".MAIN_DB_PREFIX."const WHERE ".$db->decrypt('name')."='MAIN_VERSION_LAST_INSTALL'");