Hello, I needed to perform a similar procedure and follow the solution I applied:
1 - I opened the Control Panel of my c: / xampp_old and started only the mysql service;
2 - Then I opened the Control Panel of my c: / xampp and starte Apache;
3 - I accessed the PhpMyAdmin from c: / xampp and connected to the MySql Base started in c: / xampp_old and I performed the Full Export of the Databases to .sql file;
4 - I made the export of the User accounts together with the access permissions of these banks and also saved in .sql file;
5 - I finished the PhpMyAdmin connection and stopped MySQL from the c: / xampp_old control panel;
6 - Started MySQL from the c: / xampp; Control Panel
7 - I accessed PhpMyAdmin and connected, this time you are connecting to the new MySQL;
8 - I executed the import of SQL first importing the Bank and then importing the Permissions;
9 - As I export Root User in my case my PhpMyAdmin lost the connection after the execution, being necessary to log in again, but already with the User and Password that I had configured in previous MySQL.
NOTE: I know the question was asked in time, but I hope it will be useful for anyone who needs to do this.
In My case I did the same to update my entire Xampp framework to a newer version.
If someone has difficulty performing these processes in detail, he may return with questioning.
