Centos 6 SSH "Server refused to allocate pty"

[Kephin]

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?

 

[Kephin]

Sometimes you gotta say stuff alound to think of other things.
Tried directly searching this forum.
Found this in another recent topic here:

Proxmox VE 3.x has been EOL for quite long now. I would not recommend to keep your containers running there!
If the containers worked with PVE 5.2 then they should work with PVE 5.3 - I guess you have `devpts` somewhere in the containers `/etc/fstab` - and this is not needed and does not work with LXC 3.0.1 and newer.

https://forum.proxmox.com/threads/r...er-refused-to-allocate-pty.50407/#post-234530

Commenting out this devpts rule in fstab seems to have a positive result.

Will try this on the "real" container later this evening so I can reboot the thing without causing mayhem.