diff --git a/htdocs/install/upgrade.php b/htdocs/install/upgrade.php
index 7f3d3be9bc9..8c6c16c7bb5 100644
--- a/htdocs/install/upgrade.php
+++ b/htdocs/install/upgrade.php
@@ -48,7 +48,8 @@ $versionfrom=GETPOST("versionfrom",'',3)?GETPOST("versionfrom",'',3):(empty($arg
 $versionto=GETPOST("versionto",'',3)?GETPOST("versionto",'',3):(empty($argv[2])?'':$argv[2]);
 
 $langs->load("admin");
-$langs->load("install");
+$langs->load("install");
+$langs->load("errors");
 
 if ($dolibarr_main_db_type == "mysql") $choix=1;
 if ($dolibarr_main_db_type == "mysqli") $choix=1;
@@ -152,79 +153,96 @@ if (! GETPOST("action") || preg_match('/upgrade/i',GETPOST('action')))
         print '<tr><td>'.$langs->trans("ServerVersion").'</td>';
         print '<td align="right">'.$version.'</td></tr>';
         dolibarr_install_syslog("upgrade: ".$langs->transnoentities("ServerVersion")." : $version");
-        //print '<td align="right">'.join('.',$versionarray).'</td></tr>';
+
+        // Test database version
+        $versionmindb=getStaticMember(get_class($db),'versionmin');
+        //print join('.',$versionarray).' - '.join('.',$versionmindb);
+        if (count($versionmindb) && count($versionarray)
+        	&& versioncompare($versionarray,$versionmindb) < 0)
+        {
+        	// Warning: database version too low.
+        	print "<tr><td>".$langs->trans("ErrorDatabaseVersionTooLow",join('.',$versionarray),join('.',$versionmindb))."</td><td align=\"right\">".$langs->trans("Error")."</td></tr>\n";
+        	dolibarr_install_syslog("upgrade: ".$langs->transnoentities("ErrorDatabaseVersionTooLow",join('.',$versionarray),join('.',$versionmindb)));
+        	$ok=0;
+        }
+
     }
 
     // Force l'affichage de la progression
-    print '<tr><td colspan="2">'.$langs->trans("PleaseBePatient").'</td></tr>';
-    flush();
-
+    if ($ok)
+    {
+	    print '<tr><td colspan="2">'.$langs->trans("PleaseBePatient").'</td></tr>';
+	    flush();
+    }
 
     /*
      * Delete duplicates in table categorie_association
      */
-    $couples=array();
-    $filles=array();
-    $sql = "SELECT fk_categorie_mere, fk_categorie_fille";
-    $sql.= " FROM ".MAIN_DB_PREFIX."categorie_association";
-    dolibarr_install_syslog("upgrade: search duplicate sql=".$sql);
-    $resql = $db->query($sql);
-    if ($resql)
+    if ($ok)
     {
-        $num=$db->num_rows($resql);
-        while ($obj=$db->fetch_object($resql))
-        {
-            if (! isset($filles[$obj->fk_categorie_fille]))	// Only one record as child (a child has only on parent).
-            {
-                if ($obj->fk_categorie_mere != $obj->fk_categorie_fille)
-                {
-                    $filles[$obj->fk_categorie_fille]=1;	// Set record for this child
-                    $couples[$obj->fk_categorie_mere.'_'.$obj->fk_categorie_fille]=array('mere'=>$obj->fk_categorie_mere, 'fille'=>$obj->fk_categorie_fille);
-                }
-            }
-        }
+	    $couples=array();
+	    $filles=array();
+	    $sql = "SELECT fk_categorie_mere, fk_categorie_fille";
+	    $sql.= " FROM ".MAIN_DB_PREFIX."categorie_association";
+	    dolibarr_install_syslog("upgrade: search duplicate sql=".$sql);
+	    $resql = $db->query($sql);
+	    if ($resql)
+	    {
+	        $num=$db->num_rows($resql);
+	        while ($obj=$db->fetch_object($resql))
+	        {
+	            if (! isset($filles[$obj->fk_categorie_fille]))	// Only one record as child (a child has only on parent).
+	            {
+	                if ($obj->fk_categorie_mere != $obj->fk_categorie_fille)
+	                {
+	                    $filles[$obj->fk_categorie_fille]=1;	// Set record for this child
+	                    $couples[$obj->fk_categorie_mere.'_'.$obj->fk_categorie_fille]=array('mere'=>$obj->fk_categorie_mere, 'fille'=>$obj->fk_categorie_fille);
+	                }
+	            }
+	        }
 
-        dolibarr_install_syslog("upgrade: result is num=".$num." count(couples)=".count($couples));
+	        dolibarr_install_syslog("upgrade: result is num=".$num." count(couples)=".count($couples));
 
-        // If there is duplicates couples or child with two parents
-        if (count($couples) > 0 && $num > count($couples))
-        {
-            $error=0;
+	        // If there is duplicates couples or child with two parents
+	        if (count($couples) > 0 && $num > count($couples))
+	        {
+	            $error=0;
 
-            $db->begin();
+	            $db->begin();
 
-            $sql="DELETE FROM ".MAIN_DB_PREFIX."categorie_association";
-            dolibarr_install_syslog("upgrade: delete association sql=".$sql);
-            $resqld=$db->query($sql);
-            if ($resqld)
-            {
-                foreach($couples as $key => $val)
-                {
-                    $sql ="INSERT INTO ".MAIN_DB_PREFIX."categorie_association(fk_categorie_mere,fk_categorie_fille)";
-                    $sql.=" VALUES(".$val['mere'].", ".$val['fille'].")";
-                    dolibarr_install_syslog("upgrade: insert association sql=".$sql);
-                    $resqli=$db->query($sql);
-                    if (! $resqli) $error++;
-                }
-            }
+	            $sql="DELETE FROM ".MAIN_DB_PREFIX."categorie_association";
+	            dolibarr_install_syslog("upgrade: delete association sql=".$sql);
+	            $resqld=$db->query($sql);
+	            if ($resqld)
+	            {
+	                foreach($couples as $key => $val)
+	                {
+	                    $sql ="INSERT INTO ".MAIN_DB_PREFIX."categorie_association(fk_categorie_mere,fk_categorie_fille)";
+	                    $sql.=" VALUES(".$val['mere'].", ".$val['fille'].")";
+	                    dolibarr_install_syslog("upgrade: insert association sql=".$sql);
+	                    $resqli=$db->query($sql);
+	                    if (! $resqli) $error++;
+	                }
+	            }
 
-            if (! $error)
-            {
-                print '<tr><td>'.$langs->trans("RemoveDuplicates").'</td>';
-                print '<td align="right">'.$langs->trans("Success").' ('.$num.'=>'.count($couples).')</td></tr>';
-                $db->commit();
-            }
-            else
-            {
-                print '<tr><td>'.$langs->trans("RemoveDuplicates").'</td>';
-                print '<td align="right">'.$langs->trans("Failed").'</td></tr>';
-                $db->rollback();
-            }
-        }
-    }
-    else
-    {
-        print '<div class="error">'.$langs->trans("Error").'</div>';
+	            if (! $error)
+	            {
+	                print '<tr><td>'.$langs->trans("RemoveDuplicates").'</td>';
+	                print '<td align="right">'.$langs->trans("Success").' ('.$num.'=>'.count($couples).')</td></tr>';
+	                $db->commit();
+	            }
+	            else
+	            {
+	                print '<tr><td>'.$langs->trans("RemoveDuplicates").'</td>';
+	                print '<td align="right">'.$langs->trans("Failed").'</td></tr>';
+	                $db->rollback();
+	            }
+	        }
+	    }
+	    else
+	    {
+	        print '<div class="error">'.$langs->trans("Error").'</div>';
+	    }
     }
 
 	/*
@@ -232,7 +250,7 @@ if (! GETPOST("action") || preg_match('/upgrade/i',GETPOST('action')))
 	 */
     if ($ok && preg_match('/mysql/',$db->type))
     {
-        $versioncommande=explode('.','4.0');
+        $versioncommande=array(4,0,0);
         if (count($versioncommande) && count($versionarray)
         && versioncompare($versioncommande,$versionarray) <= 0)	// Si mysql >= 4.0
         {
diff --git a/htdocs/langs/en_US/install.lang b/htdocs/langs/en_US/install.lang
index 8b078507d7c..cd43be5c0af 100644
--- a/htdocs/langs/en_US/install.lang
+++ b/htdocs/langs/en_US/install.lang
@@ -26,6 +26,7 @@ ErrorGoBackAndCorrectParameters=Go backward and correct wrong parameters.
 ErrorWrongValueForParameter=You may have typed a wrong value for parameter '%s'.
 ErrorFailedToCreateDatabase=Failed to create database '%s'.
 ErrorFailedToConnectToDatabase=Failed to connect to database '%s'.
+ErrorDatabaseVersionTooLow=Database version (%s) too old. Version %s or higher is required.
 ErrorPHPVersionTooLow=PHP version too old. Version %s is required.
 WarningPHPVersionTooLow=PHP version too old. Version %s or more is expected. This version should allow install but is not supported.
 ErrorConnectedButDatabaseNotFound=Connection to server successfull but database '%s' not found.
diff --git a/htdocs/langs/fr_FR/install.lang b/htdocs/langs/fr_FR/install.lang
index 83553a53b5b..2dd0216fbc8 100644
--- a/htdocs/langs/fr_FR/install.lang
+++ b/htdocs/langs/fr_FR/install.lang
@@ -26,6 +26,7 @@ ErrorGoBackAndCorrectParameters=Revenez en arrière et corrigez les paramètres
 ErrorWrongValueForParameter=Vous avez peut-être saisi une mauvaise valeur pour le paramètre '%s'.
 ErrorFailedToCreateDatabase=Echec de création de la base '%s'.
 ErrorFailedToConnectToDatabase=Echec de connexion à la base '%s'.
+ErrorDatabaseVersionTooLow=Version de base de donnée (%s) trop ancienne. La version %s ou supérieure est requise.
 ErrorPHPVersionTooLow=Version de PHP trop ancienne. La version %s est requise.
 WarningPHPVersionTooLow=Version de PHP trop ancienne. La version %s ou plus est recommandée. Cette version reste utilisable mais n'est pas supportée.
 ErrorConnectedButDatabaseNotFound=Connexion au serveur réussi mais base '%s' introuvable.