diff --git a/server/app/common/lists/BaseDataLists.php b/server/app/common/lists/BaseDataLists.php
index 06c813b8b5a17074c6bdd939652b610f9afefdc5..dfaa3f279c435da715a6c275b83fbcd11880d842 100644
--- a/server/app/common/lists/BaseDataLists.php
+++ b/server/app/common/lists/BaseDataLists.php
@@ -101,9 +101,13 @@ abstract class BaseDataLists implements ListsInterface
             return [];
         }
         $startTime = $this->request->get('start_time');
-        $this->startTime = strtotime($startTime);
+        if ($startTime){
+            $this->startTime = strtotime($startTime);
+        }
         $endTime = $this->request->get('end_time');
-        $this->endTime = strtotime($endTime);
+        if ($endTime){
+            $this->endTime = strtotime($endTime);
+        }
 
         $this->start = $this->request->get('start');
         $this->end = $this->request->get('end');