Can't create jails: "I/O operation on closed file"

[garyo]

I'm running FreeNAS-11.3-U1, long time user. I just discovered that I can't create a new jail from the GUI anymore: I go through the config steps but I end up getting "I/O operation on closed file". It gets to "50% 11.3-RELEASE missing, calling fetch" and then fails after a couple of minutes. But creating a jail via the cmd line works with `sudo iocage create -r 11.3-RELEASE -n 'utils'`. Is this a known issue?