diff --git a/htdocs/import/leap/lib.php b/htdocs/import/leap/lib.php
index f5b60dbca5f3d70d249e9f24b69ffa06b1031a68..c3d21678c062709c2ad35fdcd06d46e532c9cdc7 100644
--- a/htdocs/import/leap/lib.php
+++ b/htdocs/import/leap/lib.php
@@ -615,7 +615,7 @@ class PluginImportLeap extends PluginImport {
             // from trace() itself
             global $CFG;
             $oldtargets = $CFG->log_dbg_targets;
-            $oldfile    = $CFG->log_file;
+            $oldfile = isset($CFG->log_file) ? $CFG->log_file : null;
             $CFG->log_dbg_targets = $this->logtargets;
             $CFG->log_file = $this->logfile;
             $file = $line = $trace = null;