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It is a problem occurring in Fedora since 21. Firewalld somehow calls the service 'cockpit' while it isn't installed (WARNING: FedoraServer: INVALID_SERVICE: cockpit). A solution to this is to disable the service. But since there isn't any .xml file in /usr/lib/firewalld/services/ you have to create one and then disable the service. More info on: https://bugzilla.redhat.com/show_bug.cgi?id=1171114.
WORKAROUND
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Create a file /usr/lib/firewalld/services/cockpit.xml containing the following (as extracted from cockpit-ws-0.96-1.fc23.x86_64.rpm):
<?xml version="1.0" encoding="utf-8"?>
<service>
<!-- This is a firewalld service definition for Cockpit -->
<short>Cockpit</short>
<description>Cockpit lets you access and configure your server remotely.</description>
<port protocol="tcp" port="9090"/>
</service>
Service "cockpit" is then also listed in the "Firewall Configuration" (firewall-config) application.