diff --git a/app/controllers/seminars_controller.rb b/app/controllers/seminars_controller.rb
index afcc20f..3892404 100644
--- a/app/controllers/seminars_controller.rb
+++ b/app/controllers/seminars_controller.rb
@@ -345,7 +345,7 @@ class SeminarsController < ApplicationController
       sign_up = link_to(sign_up_text, seminar.get_frontend_url(seminar_url), :target=>'_blank', :title=>sign_up_text)
     end
 
-    if !seminar.registration_status.blank? && seminar.registration_status.include?('C') && seminar.contribute_start_date <= time_now && ( seminar.contribute_end_date.nil? || seminar.contribute_end_date+1 >= time_now )
+    if !seminar.registration_status.blank? && seminar.registration_status.include?('C') && (seminar.contribute_start_date.nil? || seminar.contribute_start_date <= time_now) && ( seminar.contribute_end_date.nil? || seminar.contribute_end_date+1 >= time_now )
       if @@session[:seminar_signup_id].present? && @@session[:seminar_main_id] == seminar.id
         button_text = t('seminar_signup.uploads')
         contribute_action = link_to(button_text, seminar.get_frontend_url(seminar_url, :con_upload), :title=>button_text)
@@ -616,20 +616,24 @@ class SeminarsController < ApplicationController
 
   def add_file_proc
 
-    update_params = seminar_signup_contribute_params.merge('seminar_submission_values'=>params['seminar_submission_values'])
+    update_params = seminar_signup_contribute_params.merge('seminar_submission_values'=>params['seminar_submission_values'].to_h)
     flag = true
     update_params.permit!
-    if !update_params['seminar_submission_values'].nil?
-      if update_params['seminar_submission_values']['0']['value'].class==String
-        value = update_params['seminar_submission_values']['0']['value']
-        if !value.to_s.blank?
-          flag = false
-        end
+    if update_params['seminar_submission_values'].present?
+      if update_params['seminar_submission_values']['0']['value'].nil?
+        flag = false
       else
-        update_params['seminar_submission_values']['0']['value'].each do |key,value|
-        if !value.to_s.blank?
+        if update_params['seminar_submission_values']['0']['value'].class==String
+          value = update_params['seminar_submission_values']['0']['value']
+          if !value.to_s.blank?
             flag = false
           end
+        else
+          update_params['seminar_submission_values']['0']['value'].each do |key,value|
+          if !value.to_s.blank?
+              flag = false
+            end
+          end
         end
       end
     else
@@ -668,20 +672,24 @@ class SeminarsController < ApplicationController
 
   def update
     @con = SeminarSignupContribute.find(params[:seminar_signup_contribute][:id])
-    update_params = seminar_signup_contribute_params.merge('seminar_submission_values'=>params['seminar_submission_values'])
+    update_params = seminar_signup_contribute_params.merge('seminar_submission_values'=>params['seminar_submission_values'].to_h)
     update_params.permit!
-    unless update_params['seminar_submission_values'].nil?
-      flag = true
-      if update_params['seminar_submission_values']['0']['value'].class==String
-        value = update_params['seminar_submission_values']['0']['value']
-        if !value.to_s.blank?
-          flag = false
-        end
+    if update_params['seminar_submission_values'].present?
+      if update_params['seminar_submission_values']['0']['value'].nil?
+        flag = false
       else
-        update_params['seminar_submission_values']['0']['value'].each do |key,value|
-        if !value.to_s.blank?
+        flag = true
+        if update_params['seminar_submission_values']['0']['value'].class==String
+          value = update_params['seminar_submission_values']['0']['value']
+          if !value.to_s.blank?
             flag = false
           end
+        else
+          update_params['seminar_submission_values']['0']['value'].each do |key,value|
+          if !value.to_s.blank?
+              flag = false
+            end
+          end
         end
       end
       if flag
diff --git a/app/views/seminars/con_login.html.erb b/app/views/seminars/con_login.html.erb
index 1322fa2..3463645 100644
--- a/app/views/seminars/con_login.html.erb
+++ b/app/views/seminars/con_login.html.erb
@@ -9,7 +9,7 @@
     color: red;
   }
 </style>
-<% if (@seminar.contribute_start_date <= @time_now && (@seminar.contribute_end_date.nil? or @seminar.contribute_end_date+1 >= @time_now ) rescue false) %>
+<% if (@seminar.contribute_start_date.nil? || @seminar.contribute_start_date <= @time_now) && (@seminar.contribute_end_date.nil? or @seminar.contribute_end_date+1 >= @time_now ) %>
 
 <section id="main-wrap">
   <div class="sign-in have-other-sign-in">
diff --git a/app/views/seminars/con_upload.html.erb b/app/views/seminars/con_upload.html.erb
index 8ca4b51..9046370 100644
--- a/app/views/seminars/con_upload.html.erb
+++ b/app/views/seminars/con_upload.html.erb
@@ -9,9 +9,9 @@
 	data1 = @seminar.seminar_submission_field_sets.select{|v| v.field_name=='title'}[0]
 	data2 = @seminar.seminar_submission_field_sets.select{|v| v.field_name=='description'}[0]
 	data3 = @seminar.seminar_submission_field_sets.select{|v| v.field_name=='file'}[0]
-	show1 = !(data1.disabled) rescue false
-	show2 = !(data2.disabled) rescue false
-	show3 = !(data3.disabled) rescue false
+	show1 = data1 ? !(data1.disabled) : false
+	show2 = data2 ? !(data2.disabled) : false
+	show3 = data3 ? !(data3.disabled) : false
 	name1 = data1['name'][I18n.locale]
 	name2 = data2['name'][I18n.locale]
 	name3 = data3['name'][I18n.locale]
@@ -24,7 +24,7 @@
 
 %>
 <h3 style="display:block;"><%= @seminar.title %></h3>
-<% if @seminar.contribute_start_date <= @time_now and ( @seminar.contribute_end_date.nil? or @seminar.contribute_end_date+1 >= @time_now ) %>
+<% if (@seminar.contribute_start_date.nil? || @seminar.contribute_start_date <= @time_now) && ( @seminar.contribute_end_date.nil? || @seminar.contribute_end_date+1 >= @time_now ) %>
 	<% begin %>
 	<% if !session[:seminar_signup_id].blank? %>
 	<%= t('seminar_signup.serial_number') %>: <%=@seminar_signup.display_serial_number rescue ""%>