We'll create fresh WordPress site with WP Theme Changelogs installed. You have 20 minutes to test the plugin after that site we'll be deleted.
The WP Theme Changelogs plugin allows you to view the changelog before updating a theme, very similiar to the available changelogs for plugins.
The plugin parses the readme.txt of the theme to get the changelog details. In order to work, your theme must have a valid readme.txt including a changelog section.