Symptoms

The thumbnail of the profile picture located on the top right corner of the navigation is missing. This occurs for all users using different browsers.

Diagnosis

Using the Firebug or Developer Tool, the URL of the thumbnail returns a "HTTP 404 Not Found" error. The URL is either incorrect or uses a different context path 

Cause

The thumbnail cache is corrupted, possibly due to the change of Confluence Server Base URL

Resolution

• Stop Confluence

• Backup the thumbnails folder in the Confluence Home directory. 

• Delete the thumbnails folder
  As mentioned in our documentation, it's safe to remove it as Confluence will regenerate thumbnails as required
• Start Confluence