> Open XAMPP Control Panel (run as administrator!).
> Stop services and uninstall them from services list if any.
> Close XAMPP Control Panel.
> Keep backup of htdocs, mysql\data directories and phpmyadmin\config.inc.php file.
> Delete C:\xampp directory.
> Download new XAMPP installer.
> Install XAMPP to the same location (C:\xampp).
> Copy your websites only from htdocs backup folder to the new htdocs folder (C:\xampp\htdocs).
> Replace C:\xampp\mysql\data folder with the old one (backup).
> Replace C:\xampp\phpmyadmin\config.inc.php file with yours.
> Upgrade MySQL system databases. Run command line as administrator and execute:
C:\xampp\mysql\bin\mysql_upgrade.exe -uroot -p --force