Hey, there is an issue that affect some local installs of XAMPP running a non-English version of XAMPP and / or Microthemer. Going to General > Preferences > Compatibility > “Load a legacy version of jQuery” is the fix, as you say.
But sometimes the error means it’s not possible to even change that setting. In that case, try temporarily setting the WordPress dashboard language to English via the WordPress settings page. Then try again. It may also help if you use the standalone Microthemer Preferences page (see the option under the main Microthemer option in the WordPress sidebar menu).