FOR VERSION 3.0.9 OR EARLIER ONLY
If you installed Semplice 2.0 (or above) you might get the notice that your theme root folder must be '/semplice'. Since the One-click Update of the theme always installs the updated theme into '/semplice' in your themes folder its necesarry that the theme is installed in this folder.
That means if you previously installed semplice via FTP in folders like '/semplice_1_2' you will have to make a fresh install of Semplice 2.0 (or above). Please read our documentation on how to do that:
Guide: Install Semplice in WordPress.
Important Note: Please don't just change the folder name manually from '/yourname' to '/semplice' because this will result in an error. Instead please do a fresh install of Semplice 2.0 (or above) like described in the guide.