The firewalld daemon must be already started. If it is not, then start it by systemctl start firewalld. Reported by: pdancak https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/9/html/configuring_and_using_a_cups_printing_server/configuring-printing_configuring-and-using-a-cups-printing-server#annotations:8691cdcd-6037-4cb0-893d-9962d15c3037
I didn't want to create bugzilla, just wanted to write down a note for doc. people.