diff --git a/app/api/mobile/entities/user.rb b/app/api/mobile/entities/user.rb
index 1f52ae841..9112e7ec5 100644
--- a/app/api/mobile/entities/user.rb
+++ b/app/api/mobile/entities/user.rb
@@ -15,13 +15,13 @@ module Mobile
                 when :img_url
                   url_to_avatar(u)
                 when :gender
-                  u.user_extensions.gender.nil? ? 0 : u.user_extensions.gender
+                  u.nil? || u.user_extensions.nil? || u.user_extensions.gender.nil? ? 0 : u.user_extensions.gender
                 when :work_unit
                   get_user_work_unit u
                 when :location
                   get_user_location u
                 when :brief_introduction
-                  u.user_extensions.brief_introduction
+                  u.nil? || u.user_extensions.nil? ? "" : u.user_extensions.brief_introduction
               end
             end
           end
diff --git a/app/services/courses_service.rb b/app/services/courses_service.rb
index a96bc0fbe..aa216d755 100644
--- a/app/services/courses_service.rb
+++ b/app/services/courses_service.rb
@@ -345,7 +345,7 @@ class CoursesService
   def course_dynamic(params,current_user)
 
     @user = User.find(params[:id])
-    if !current_user.admin? && !@user.active?
+    if current_user.nil? && !current_user.admin? && !@user.active?
       raise '404'
       return
     end
diff --git a/db/migrate/20150415032102_change_file_digests.rb b/db/migrate/20150415032102_change_file_digests.rb
new file mode 100644
index 000000000..a8fe5febf
--- /dev/null
+++ b/db/migrate/20150415032102_change_file_digests.rb
@@ -0,0 +1,9 @@
+class ChangeFileDigests < ActiveRecord::Migration
+  def up
+    change_column :zip_packs, :file_digests, :text
+  end
+
+  def down
+    change_column :zip_packs, :file_digests, :string
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index a8ade8ed0..e4c11e8ce 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -11,7 +11,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20150402015402) do
+ActiveRecord::Schema.define(:version => 20150415032102) do
 
   create_table "activities", :force => true do |t|
     t.integer "act_id",   :null => false
@@ -1458,7 +1458,7 @@ ActiveRecord::Schema.define(:version => 20150402015402) do
     t.string   "file_path"
     t.integer  "pack_times",   :default => 1
     t.integer  "pack_size",    :default => 0
-    t.string   "file_digests"
+    t.text     "file_digests"
     t.datetime "created_at",                  :null => false
     t.datetime "updated_at",                  :null => false
   end