diff --git a/backup/restorelib.php b/backup/restorelib.php
index cf4a1c45a94..b1899cf3a7c 100644
--- a/backup/restorelib.php
+++ b/backup/restorelib.php
@@ -4051,6 +4051,10 @@ define('RESTORE_GROUPS_GROUPINGS', 3);
                 //Iterate
                 $counter = 0;
                 foreach ($list as $dir) {
+                    //Avoid copying maintenance.html. MDL-18594
+                    if ($dir == 'maintenance.html') {
+                       continue;
+                    }
                     //Copy the dir to its new location
                     //Only if destination file/dir doesn exists
                     if (!file_exists($dest_dir."/".$dir)) {