Remember that the HTDOCS folder is in the XAMPP folder, so when you upgrade, everything in HTDOCS is lost.
this is a silly file structure, HTDOCS should reside outside the core functionality of XAMPP so upgrading doesn't mean losing all your sites (which just happened to me)...worse still osx permanently erases everything, bypassing the trash, so it is unrecoverable.
learn from my mistake though it would be good if the xampp team prevented this from happening in the future with better folder structuring.