My galleries show a 404 error
If you are experiencing a 404 error for your galleries, it is possible something happened to your permalink settings. In your WordPress admin, go to Settings > Permalinks and simply hit save (you don’t have to change anything). This will reset the settings in the database and in most cases fixes the issue.
If that still does not work, you may have a theme or plugin which creates a “gallery” custom post type and there is a conflict with Sunshine. Go to Sunshine > Settings > General tab and at the bottom are options to customize the Sunshine URLs. You may need to change the default gallery to something else.