I just installed Mac OSX Catalina and found out that some of my directories have been moved. I had a directory /data/ in the root(/) of my file system.
I tried creating directory before looking up where its as I thought its gone forever. But if you try to create a directory in the root of your Mac OSX it is no longer possible due to security and potential vulnerabilities in the operating system. The root directory is now read-only and you will get an error saying read only file system if you try to create a directory.
After a quick search I found that the files have been moved under:
/Users/Shared/Relocated Items
If you had setup any apache2 or mysql configurations they have been set to default and can be found inside /Users/Shared/Relocated Items/Configuration or the files have renamed for example my apache’s vhosts file in /etc/apache2/extra was renamed to something like httpd-userdir.conf~previous. So just rename them back to after adjusting your vhosts and you are good to go!.