diff --git a/php/libraries/NDB_BVL_Instrument.class.inc b/php/libraries/NDB_BVL_Instrument.class.inc
index 8e88e437758..a1571d58ec7 100644
--- a/php/libraries/NDB_BVL_Instrument.class.inc
+++ b/php/libraries/NDB_BVL_Instrument.class.inc
@@ -2860,7 +2860,9 @@ abstract class NDB_BVL_Instrument extends NDB_Page
         // Disable form if data entry is complete
         $user      = $request->getAttribute("user");
         $sessionID = $request->getQueryParams()["sessionID"];
-        $timepoint = \Timepoint::singleton(new SessionID($sessionID));
+        if ($sessionID !== null) {
+            $timepoint = \Timepoint::singleton(new SessionID($sessionID));
+        }
 
         // create an instrument status object
         $status = new \NDB_BVL_InstrumentStatus($this->loris);