I was able to recover a system that had this happen to it. I think the key bit was to run:
<code>dpkg --purge libappconfig-perl libjs-extjs libtemplate-perl</code>
Not totally sure about all three packages, and I sure don't want to go through that again.
Just recording here for future...
Ran into this problem today, running a new-ish kernel. 4.4.6-1-pve
Running /etc/init.d/pve-cluster restart on one node fixed the issue on all nodes. Did I just happen to guess correctly on the broken node?
pvecm status said everything was fine.
I could read files inside /etc/pve