diff --git a/app/models/configuration.rb b/app/models/configuration.rb
--- a/app/models/configuration.rb
+++ b/app/models/configuration.rb
@@ -103,7 +103,11 @@
 
   def self.read_one_key(key)
     conf = Configuration.find_by_key(key)
-    return Configuration.convert_type(conf.value,conf.value_type)
+    if conf
+      return Configuration.convert_type(conf.value,conf.value_type)
+    else
+      return nil
+    end
   end
 
   def self.read_grading_info