firewalld: ERROR: Calling post func<function ifcfg_set_zone_of_interface at ...>failed: unsupported format ... at index 1

Issue

• When checking the status of firewalld we are seeing the following error:

# systemctl status firewalld
● firewalld.service - firewalld - dynamic firewall daemon
   Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled)
   Active: active (running) since Fri 2017-03-24 08:28:28 EDT; 1h 59min ago
     Docs: man:firewalld(1)
 Main PID: 17233 (firewalld)
   CGroup: /system.slice/firewalld.service
           └─17233 /usr/bin/python -Es /usr/sbin/firewalld --nofork --nopid

Mar 24 08:28:28 hostname systemd[1]: Starting firewalld - dynamic firewall daemon...
Mar 24 08:28:28 hostname systemd[1]: Started firewalld - dynamic firewall daemon.
Mar 24 08:28:29 hostname firewalld[17233]: WARNING: ip6tables not usable, disabling IPv6 firewall.
Mar 24 08:28:29 hostname firewalld[17233]: ERROR: Calling post func <function ifcfg_set_zone_of_interface at 0x24bcc08>(('', 'ens182')) failed: unsupported format ... at index 1
Hint: Some lines were ellipsized, use -l to show in full.

• We are also seeing the following error in /var/log/messages:

Mar 29 11:3145 hostname firewalld: ERROR: Calling post func <function ifcfg_set_zone_of_interface at 0xb50c08>(('', 'ens192')) failed: unsupported format character ':' (0x3a) at index