I have been using XAMMP on my mac, it was working fine before OS update to Catalina.
I am not able to start MySQL and Apache. I read the blog that Apache and Php are built-in with Mac OS Catalina, this might be the issue, I have been using 64-bit XAMMP
The manager-osx is not working, but you can start it through the terminal. Go to /Applications/XAMPP/xamppfiles and type: sudo ./xampp start