Index: mod/assignment/backuplib.php
===================================================================
--- mod/assignment/backuplib.php	(revision 15616)
+++ mod/assignment/backuplib.php	(working copy)
@@ -53,6 +53,11 @@
             $assignment = get_record('assignment','id',$assignment);
         }
     
+        if (empty($assignment->assignmenttype)) {
+            // No assignment type will cause fatal error below in require_once so bail out now
+            return false;
+        }
+
         $status = true;
 
         //Start mod