500/502 error on Gitlab Pages

Hello everyone, I have installed a gitlab server. However, I usually get 500/502 error on the Gitlab pages! It may restore after gitlab-ctl reconfigure , but I still think it maybe something wrong with my server to cause often error on it!

I find the following error in /var/log/gitlab/gitlab-rails/production.log

Started GET "/Facail/home-facial/tree/develop" for 125.227.129.228 at 2017-01-18 04:07:25 +0000
Processing by Projects::TreeController#show as HTML
Parameters: {"namespace_id"=>"Facail", "project_id"=>"home-facial", "id"=>"develop"}
Completed 500 Internal Server Error in 1261ms (ActiveRecord: 114.7ms)

ActionView::Template::Error (MISCONF Redis is configured to save RDB snapshots, but is currently not able to        persist on disk. Commands that may modify the data set are disabled. Please check Redis logs for details about the error.):
  25:       = link_to assigned_issues_dashboard_path, title: 'Issues', class: 'dashboard-shortcuts-issues' do
  26:         %span
  27:           Issues
  28:           %span.count= number_with_delimiter(cached_assigned_issuables_count(current_user, :issues, :opened))
  29:     = nav_link(path: 'dashboard#merge_requests') do
  30:       = link_to assigned_mrs_dashboard_path, title: 'Merge Requests', class: 'dashboard-shortcuts-merge_requests' do
  31:         %span
app/helpers/issuables_helper.rb:141:in `cached_assigned_issuables_count'
app/views/layouts/nav/_dashboard.html.haml:28:in `block (2 levels) in _app_views_layouts_nav__dashboard_html_haml__112997484186146491_70002006084560'
app/views/layouts/nav/_dashboard.html.haml:25:in `block in _app_views_layouts_nav__dashboard_html_haml__112997484186146491_70002006084560'
app/helpers/tab_helper.rb:55:in `nav_link'
app/views/layouts/nav/_dashboard.html.haml:24:in `_app_views_layouts_nav__dashboard_html_haml__112997484186146491_70002006084560'
app/views/layouts/_page.html.haml:15:in `_app_views_layouts__page_html_haml___4136658417212639126_70002005279600'
app/views/layouts/application.html.haml:11:in `_app_views_layouts_application_html_haml__4278211878474165529_70002013455020'
app/views/layouts/project.html.haml:25:in `_app_views_layouts_project_html_haml__1395401247321328211_70001975658480'
app/controllers/projects/tree_controller.rb:27:in `show'
lib/gitlab/middleware/multipart.rb:93:in `call'
lib/gitlab/request_profiler/middleware.rb:15:in `call'
lib/gitlab/middleware/go.rb:16:in `call'

Is there anyone realize the log and can tell me how to improve it? THX