script will downlaod missing "cnf" folders to your ubuntu local repository.
copy apt-mirror file to /usr/bin/ and replace original file which is not maintained for several years :(
Fetched 492 kB in 1s (581 kB/s)
Reading package lists... Done
E: Failed to fetch http://10.20.10.94/ubuntu/mirror/ftp.sh.cvut.cz/ubuntu/dists/focal/main/cnf/Commands-amd64 404 Not Found [IP: 10.20.10.94 80]
E: Failed to fetch http://10.20.10.94/ubuntu/mirror/ftp.sh.cvut.cz/ubuntu/dists/focal-updates/main/cnf/Commands-amd64 404 Not Found [IP: 10.20.10.94 80]
E: Failed to fetch http://10.20.10.94/ubuntu/mirror/ftp.sh.cvut.cz/ubuntu/dists/focal-security/main/cnf/Commands-amd64 404 Not Found [IP: 10.20.10.94 80]
E: Some index files failed to download. They have been ignored, or old ones used instead.
copy "post-mirror-cnf.sh" file to /var/www/html/ubuntu/var directory based on what you have in your config /etc/apt/mirror.list
For example I have in my /etc/apt/mirror.list config file:
set base_path /var/www/html/ubuntu
set var_path $base_path/var
edit config file /etc/apt/mirror.list and put your new post mirror script. If you have your own post mirror script, just include the "post-mirror-cnf.sh" file into your post mirror script.
set postmirror_script $var_path/post-mirror-cnf.sh