Some recent-ish Proxmox 5 updates seems to have caused an issue on my end with Centos 6 containers. I have a couple of Centos 6 containers still that have been migrated from Proxmox 3.5 to 5. (so openvz to lxc) These used to work fine, but in a recent update round SSH "became broken", getting an "Server refused to allocate pty" error upon logging in. Console via GUI also not responsive. I have to connect to the container by oppening ssh to the node and then using lxc-attach. Searching for the error reveals several (old) topics of things to try but none seem to work. I've restored a backup as a test container to fiddle with, and sure enough moving it between updated (updated today) and "non-updated" (last node reboot was about three months ago) nodes results in having or not having this error upon respectively trying to login on SSH. Centos 7 containers do not seem affected by this. I'm kind of lost as to where to go from here. Is this issue known, does anybody have any tips?