title: gitlab 500 errors in the admin area
body: <p><strong>How to reproduce:</strong></p>
  
  <ol>
  <li>login as admin</li>
  <li>go into the admin menu</li>
  <li>click on overview - runners</li>
  <li>or click save in the settings</li>
  </ol>
  
  <p>Result: 500 Error: Whoops, something went wrong on our end.</p>
  
  <p><strong>Which system is running?</strong></p>
  
  <p>RHEL 7, outbound gitlab with Nginx and passengers</p>
  
  <p><strong>Errors:</strong></p>
  
  <pre><code>OpenSSL::Cipher::CipherError ():
  
  lib/gitlab/crypto_helper.rb:27:in `aes256_gcm_decrypt'
  app/models/concerns/token_authenticatable_strategies/encrypted.rb:55:in `get_token'
  app/models/concerns/token_authenticatable_strategies/base.rb:27:in `ensure_token'
  app/models/concerns/token_authenticatable_strategies/encrypted.rb:42:in `ensure_token'
  
  
  ActionView::Template::Error ():
      37: 
      38:     .col-sm-6
      39:       .bs-callout
      40:         = render partial: 'ci/runner/how_to_setup_runner',
      41:                  locals: { registration_token: Gitlab::CurrentSettings.runners_registration_token,
      42:                            type: 'shared',
      43:                            reset_token_url: reset_registration_token_admin_application_settings_path }
  </code></pre>