diff --git a/app/controllers/main_controller.rb b/app/controllers/main_controller.rb
--- a/app/controllers/main_controller.rb
+++ b/app/controllers/main_controller.rb
@@ -63,7 +63,8 @@
     @submission.user = user
     @submission.language_id = 0
     if (params['file']) and (params['file']!='')
-      @submission.source = params['file'].read 
+      @submission.source = File.open(params['file'].path,'r:UTF-8',&:read) 
+      @submission.source.encode!('UTF-8','UTF-8',invalid: :replace, replace: '')
       @submission.source_filename = params['file'].original_filename
     end
     @submission.submitted_at = Time.new.gmtime
diff --git a/app/controllers/users_controller.rb b/app/controllers/users_controller.rb
--- a/app/controllers/users_controller.rb
+++ b/app/controllers/users_controller.rb
@@ -124,6 +124,7 @@
       @histogram[:data][d.to_i] += 1 if d < range
 
       @summary[:count] += 1
+      next unless sub.problem
       problem[sub.problem] = [problem[sub.problem], (sub.points >= sub.problem.full_score) ? 1 : 0].max
     end