I had a similar problem with XAMPP. Apache just lost access to my external drive, which I included via a symlink. Even giving "Full Disk Access" to the httpd webserver didn't help.
The final solution was to start Apache with the sudo command:
sudo Applications/XAMPP/bin/apachectl startdid the job for me. Please note that
sudo apachectl startwould start the Apache that comes with macOS and thus wouldn't be used with XAMPP (and MAMP as well, I guess).
