diff --git a/app/controllers/test_controller.rb b/app/controllers/test_controller.rb
--- a/app/controllers/test_controller.rb
+++ b/app/controllers/test_controller.rb
@@ -101,7 +101,7 @@
     end
     @test_requests = []
     @user.test_requests.each do |ts|
-      if ts.problem.available
+      if ts.problem and ts.problem.available
         @test_requests << ts
       end
     end