I just hid the users, full output is included
Permissions on the file are:
-rw-r----- 1 root root 0 Apr 11 07:55 advanced-cache.php
I have given permission to the root user (I realise I probably shouldn’t be using this user but I understand the risks)
sudo chown -R www-data:www-data /var/www
sudo usermod -aG www-data root
sudo chown -R 774 /var/www