When I tried to add to my ipset, (firewall-cmd --permanent --ipset=groupips --add-entry=XXX.XXX.XX.0/24) 
 I received the following error:

Error: IO_Object_XMLGenerator instance has no attribute '_out'

This subsequently made my ipset file empty, and as a result, I can not ssh into the machine.

Can I just recreate the ipset file under /etc/firewalld/ipsets and try to firewall-cmd --reload?

What is this error and how do I fix it?

I am currently running redhat release 7.2. Firewalld is at firewalld-0.4.3.2-8, with
no yum updates outstanding.

Kelley Trombly-Freytag