Centos 6 SSH "Server refused to allocate pty"


Renowned Member
Apr 21, 2015
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?
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.


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.
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