app/src/Repository/Venta/Factura.php

@@ -168,7 +168,7 @@ class Factura extends Ideal\Repository
         $query = $this->connection->getQueryBuilder()
             ->select()
             ->from($this->getTable())
-            ->where('venta_id = :venta_id AND index = :index');
+            ->where('venta_id = :venta_id AND `index` = :index');
         return $this->fetchOne($query, ['venta_id' => $venta_id, 'index' => $index]);
     }
 }