Symptoms

1. On the Dashboard, nothing is shown. The drop-down menus are not clickable
   
2. Even going back to the Plugins page, nothing is rendered and the UPM is not showing
   

Cause

The avatar-picker module is disabled.

Workaround

1. Using Google Chrome, download the REST Console extension
2. Fill up the necessary information to fire the request again
   
   Request URI: http://localhost:8514/jira/rest/plugins/1.0/jira.webresources-key/modules/avatar-picker-key
   
   Replace the localhost:8514/jira with the URL of your instance
   
   
   Content Headers: application/vnd.atl.plugins.plugin.module+json
   Raw Body: {"name":"avatar-picker","links":{"self":"/jira/rest/plugins/1.0/jira.webresources-key/modules/avatar-picker-key"},"enabled":true}

1. 
   
   
   Make sure you click on Basic Auth and fill up the username and password
   
   
2. The avatar-picker module should be re-enabled again