diff --git a/app/models/problem.rb b/app/models/problem.rb
--- a/app/models/problem.rb
+++ b/app/models/problem.rb
@@ -45,7 +45,7 @@
                                      import_params[:memory_limit],
                                      import_params[:checker_name],
                                      import_to_db)
-      problem.errors.add_to_base('Import error.')
+      problem.errors.add(:base,'Import error.')
     end
 
     return problem, importer.log_msg
@@ -85,17 +85,17 @@
                                            DEFAULT_MEMORY_LIMIT)
 
     if time_limit<=0 or time_limit >60
-      problem.errors.add_to_base('Time limit out of range.')
+      problem.errors.add(:base,'Time limit out of range.')
     end
 
     if memory_limit==0 and params[:memory_limit]!='0'
-      problem.errors.add_to_base('Memory limit format errors.')
+      problem.errors.add(:base,'Memory limit format errors.')
     elsif memory_limit<=0 or memory_limit >512
-      problem.errors.add_to_base('Memory limit out of range.')
+      problem.errors.add(:base,'Memory limit out of range.')
     end
 
     if params[:file]==nil or params[:file]==''
-      problem.errors.add_to_base('No testdata file.')
+      problem.errors.add(:base,'No testdata file.')
     end
 
     checker_name = 'text'